CA2190944A1

CA2190944A1 - Apparatus for switching optical signals and method of operation

Info

Publication number: CA2190944A1
Application number: CA002190944A
Authority: CA
Inventors: Richard H. Laughlin
Original assignee: Individual
Current assignee: Optical Switch Corp
Priority date: 1994-05-27
Filing date: 1995-05-18
Publication date: 1995-12-07
Also published as: ATE225946T1; US5553175A; US5444801A; US5566260A; DE69528526D1; EP0760961A1; US5647033A; US5555558A; WO1995033219A1; EP0760961B1; EP0760961A4; JPH10503853A

Abstract

The present invention provides an apparatus (74 and 200) for switching an optical signal from an input optical fiber (210) to one of a plurality of output optical fibers (214 and 216). The apparatus (74 and 200) includes a collimator (76) for collimating an input optical signal into a collimated beam (216) at an angle with respect to a reference and a decollimator (78) for focusing the collimated beam to an output optical signal (220). The present invention also includes a reflector (92, 208, 218 and 222) for reflecting the collimated beam. The reflector (92 and 208) has a plurality of positions for changing the angle of the collimated beam (216) with respect to the reference so that the output optical signal (220) is focused on one of the plurality of output optical fibers (214 and 216).

Description

WO 95/33219 r~ 17 . .
,. 1 APPARATUS FOR ~wl~l ClllN(:; OPTICAL
SIGNALS AND METHOD OF OPERATION
TEc~TNI-~T. FIT~T~n OF TT~E INVENTION
This invention relates in general to the f ield of optical processing 6ystems, and more particularly to optical switches used in f iber optic networks .

SUE51IME SHEE (I~U E Z~

WO 9!5/33219 r~ c~-l7 2 2 1 9~944 RAl Kl;~( )UNL) OF TT~ INVEN~ION
In f iber optic systems, various methods have been previously developed for switching optical signals between f iber optic cables . These previously developed methods can be classif ied into three categories:
electrical, solid-state, and mechanical.
Electrical switches convert an optical signal to an electrical signal and then switch the electrical signal by conventional switching techniques. Electrical switches then convert the electrical signal back into an optical 6ignal. Electrical switching of optical signals is faster then when using existing ~ nic~l switches, but is also significantly more expensive. Additionally, electrical switching of optical signals is bandwidth limited, i.e., a converted electrical signal cannot "carry" all of the information in an optical signal.
This limitation ~LC V~=IILS electrical switching of optical signals from ut i 1 i ~; ng the full optical bandwidth available with f iber optics, and severely limits the advantages available when using fiber optics.
Solid-state optical signal switches typically use titanium diffused lithium niobate devices. Solid-6tate switches have f ast switching speeds, less than one nanosecond, and the same bandwidth capacity as fiber optics. 601id-state switches, however, cost 30 to 100 times more than existing - ~nic~l switches and have insertion losses ~Yc~ n~ 20 times those for existing ^h ~ n i rs~ 1 switches .
Previously developed ~ nic;tl switches for switching optical signals are typically lower in cost than electrical or solid-state optical switches, provide low insertion loss, and are compatible with the bandwidth of fiber optics. Currently available optical - ~-h In switches, however, are relatively slow, with switching speeds of approximately 5 to 50ms.

WO 9513321~ r~ . 17 The sctuators used in some eYisting -- -ni,-Al switches result in their slow switching speed.
Previously developed optical - ; rA l switches typically move mirrors or prisms or rotate the fiber to change the signal path for an optical signal.
Alternatively, existing r--hAnicAl switches change a signal's path by moving the input fiber itself to align with the desired output fiber. Both of these techniques require moving large masse6 (mirrors or prisms) in a minimum time period. Existing optical -- -niCAl switches may use solenoids and motors or piezo-electric trAnC~I"''C" D as the actuators.
Recent dev~ Ls in network systems, such as SONET and aDy.l.;l.~;ul-uus transfer mode (ATM) packet switching systems, require optical signal switching speeds of 101Ls or less. This speed is approximately 1, 000 times faster than available through previously developed optical r--hAnicAl switches. Therefore, in order to obtain the benefits of fiber opti neL ~Lk., more expensive electrical or solid-state switches must be used. Additionally, electrical and solid-state fiber optic switches experience losses that af f ect network otio=.

STlMMARY OF l~T~ TNVENTION
Therefore, a need has arisen for a switch for collrl ln~ optical signals between fiber optics that eliminates the problems as60ciated with previously developed optical switches.
A need has arisen for a low cost, reliable, fast optical r- `9n;~-Al switch for coupling optical signals between optical f ibers .
An additional need exists f or a f iber optic switch having suf~icient isolation between rhAnnelR
Yet another need exists f or a f iber optic switch with a switching speed of approximately lO~Ls or less.
In accordance with the present invention, a f iber optic switch is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed optical signal switching devices and techniques .
One aspect of the present invention provides an ~l~yal~ltu~ for switching an optical signal from an input optical fiber to one of a plurality of output optical fibers. The ~aL~Lus ;n~ F a collimator for collimating an input optical signal into a collimated beam at an angle with respect to a ref erence and a decol 1 ir-tor for focusing the collimated beam to an output optical signal. The present invention also ;n~ a reflector for reflecting the collimated beam.
The reflector has a plurality of positions for ~hAn~;ng the angle of the collimated beam with respect to the reference so that the output optical signal is focused on one of the plurality of output optical fibers.
Another aspect of the present invention provides an o,r ~,Lus for 5witching a plurality of optical signals from a plurality of input optical fibers to a plurality of output optical f ibers . The apparatus ; n~ 9c a collimator for collimating each input optical signal into a collimated beam at an angle with respect to a reference WO 95/33219 P~ Ju, C
5 21 90944 s 17 and a elero~ tor for focusing each collimated beam to an output optical signal. The A~a~lLus further includes a reflector for reflecting each collimated beam.
The reflector has a plurality of positions for changing the angle of each collimated beam with respect to its reference 50 that each output optical signal i5 focused on one of the plurality of output optical fibers.
Yet another aspect of the present invention provides a method for switching an optical signal from an input optical fiber to one of a plurality of output optical f ibers . The method includes collimating the input optical signal into a collimated beam at an angle with respect to a reference, and then rh:~n~;ng the angle of the collimated beam by an amount. The collimated beam is then decollimated and focused after its angle has been changed to one of the plurality of output optical fibers.
Each amount the angle of the beam changes ~,C.L L t ~ ds to switching the collimated beam to a different output optical f iber .
The present invention provides numerous terhn;r~l advantages. A terhn;r~l adva~Lay~: of the present optical switch is its low cost in comparison to existing optical E~witches .
The present f iber optic switch provides an additional terhn;r~l advantage of a fast switching speed, ~t approximately lO~s ~or one c~ml~o~l ~ of the invention .
The present switch provides a terhn;rAl advc...l age of being configurable into different types of switches, ;nrlllrl~n~ one fiber to several fibers or several fibers to several other f iberc . The present switch can be configured as a reversing bypass or ~Luss~ r switch.
The present switch may be also c;~cr~rlocl to provide a large switch array for switching optical signals in a 3 5 network .

W0 95133219 2 i 9 0 9 4 4 F~ rI7 The present optical switch is a reflective surface based system having less -nts than previously developed optical r- ~n;r ~l switches, and therefore, is less ex~ensive to build.
The present switch may be manufactured using existing materials and terhnirrloc that contribute to its to< hnir-l advantage of low cost.
Yet another torhn;r_l advantage of the present switch is its low insertion loss, typically less than ldB. The isolation provided by the present switch eliminates cross-talk in a network employing the present switch .
The present switch provides a terhn i r -1 advantage of being suitable with many applications of f iber optics .
It may be integrated into SONET or ATM networks to provide low cost switching.
Yet another torhni~r~l advantage of the present optical switch is that it may be used as a variable beam splitter, attenuator, or modulator.

WO95/33Z19 P. llu.,._. '17 ~ 2 1 90944 RiRTFF DESCRIPTION OF ~F. DR~AWINGS
For a more complete understanding of the present invention and advantages thereof, ref erence is now made to the following description taken in C~ll; u--~;Lion with the :~l , nying drawings in which like reference numbers indicate like features and wherein:
FIGURE 1 illustrates the collimation of a beam;
FIGURE 2 shows the collimation and decollimation of a beam to shift the spatial location of an image;
FIGURES 3A and 3B illustrate the input and output focal planes for the lenses in FIGURE 2;
FIGURE 4 depicts an Pmho~ L of the present invention;
FIGURE 5 illustrates the input focal plane of the optical switch of FIGURE 4;
FIGURES 6A and 6B illustrate two conf igurations of the output focal plane of the optical switch of FIGURE 4;
FIGURE 7 depicts a single lens ~ of the present invention;
FIGURES 8A and 8B illustrate a configuration for the focal plane of the single lens optical switch of FIGURE 7;
FIGURE 9 depicts an alternate : ' - ' i - of a single lens optical switch;
FIGURES 10A-lOC illustrate an: ' '; L of the pre6ent invention configured for reversing bypass operation;
FIGURES llA-llD show an : '- - ' i-- L of the present invention configured for ~:Luss-l:c.r switching;
FIG~RE 12 illustrates an ~ho~l;- L of the present invention employing rLu_L.~-ted total internal reflection (FTIR);
FIGURES 13A and 13B show a cascade of two switches of FIGURE 12 to provide a lx4 switch;
FIGURES 14A and 14B show an: ' -'i- L of a lx2 f iber optic switch;

Wo 95/33219 r~ .r-~l7 8 ~ ~ 9~q4~
FIGURE 15 illustrates an ~ ~-';r ~ of the present invention employing a single lens;
FIGI~RE 16 shows an ~ L of the present invention employing two lenses;
5FIGURE 17 illustrates an alternate e~mho~ Of the present invention for double action switching;
FIGURE 18 pre6ents a graph of rLl.~L~ ed total internal refl~c~; nnC as a function of spacing and angle of ; nrid-~n~e;
FIGI~RES l9A-19C illustrate a 4x4 cro66-bar switch configuration employing the present invention; and FIGURE 20 illustrates a switch array employing the present invention.

W0 95/33219 ~ 17 2 ~ 90944 D~TATT,~n D~RIP'rION OF TT~ TNVENTION
Preferred: ' ~;r ~s of the present invention are illustrated in the f igures, like numerals being used to refer to Cur L~ ; n~ parts of the various drawings .
FIGURE 1 illustrates the collimation of a beam with a lens and is helpful in understanding the theory and operation of the present switch. FIGURE 1 includes grid 10 having X-axis 12 and Y-axis 14 for reference only.
Collimator or lens 16 is positioned along X-axis 12 at a distance 18 from Y-axis 14 at the focal length for lens 16. Focal plane 20 for lens 16 is - inAl ly shown in FIGllRE 1 on Y-axis 14. FIGURE 1 also includes an image originating at point 22 along ~ocal plane 20 for lens 16.
The image at point 22 is displaced from X-axis 12 by displ A ' 24 .
The image at point 22 is collimated into parallel beams 26 by lens 16. Parallel beams 26 include center beam 28, top beam 30, and lower beam 32, shown for illustrative ~uL~oses only. Lens 16 encodes the spatial position or displ Al- ' 24 with reference to X-axis 12 of point 22 in focal plane 20 to angle ~ 34. The spatial position of the image at point 22 defines angle ~ 34 of collimated beams 26. Angle ~ 34 may be defined by the relat i on~h; p (~ Zeng~h 18 ) (1 Therefore, the spatial position of point 22 defines the angle ~ 34 of beams 26 with respect to optical X-axis 12.
FIGURE 2 shows two collimating lenses placed back to back for transferring an input image at point 22 of input 36 to output 38 at point 39. FIGURE 2 ;n~ F lens 16 of FIGURE 1 and decollimator or lens 40 also positioned W0 95/33219 r~ c r77 lo 2 1 90944 along X-axis 12. Lens 40 decollimates parallel beams 26 and decodes the angle of the collimated beams back to a disp~ when lens 40 focuses the beams at point 39 on focal plane 42 associated with lens 40.
Lenses 16 and 40 placed back to back act as a conventional imaging lens with their magnif ication equal to the ratio of their focal lengths. When the focal lengths of lenses 16 and 40 are equal, there is no magnification, rather the image is merely transferred to output 38. Lenses 16 and 40, with equal focal lengths, form an imaging lens which has the IJLoptLLy of providing an output image at point 39 that is inverted and r~:v~:Laed from the input image at point 22. Output image point 39 is displaced by ~ rl~ L 48 from X-axis 12 in accordance with the relatinn~hir described in the c~ inn~: of Equation 1. Displ ;l~ ~ 48 is equal in magnitude to ~ pl :,. t 24 . In this way, the input image point 22 iB inverted and r~vl:~aed at output focal plane 42 at image point 39. That i8, image point 22 on input focal plane 20 is imaged to output focal plane 42 at an equal but opposite disp~ A~ ~ 48 from the optical center of lenses 16 and 40 ~ as~ ed by X-axis 12 of FIGURE 2 . This concept of spatial c-n~'o~1; ng of a signal ' 8 ~ ;pl;~r ~ into an angle during collimation and 5ll1 Je~lu- - deco~;n~ of the angle to the displ~ -during decollimation of the beam can be used to route or switch optical signals to various output optical r!h;lnn~
or f ibers .
It is noted that while lenses 16 and 40 are both 3 0 centered along X-axis 12 in FIGURE 2, that the lenses need not be in alignment to form an imaging lens.
Tilting either lens 16 or 40 with respect to X-axis 12 merely adds to an imaged signal's displ~ L on the output focal plane. In a like manner, translating either lens 16 or 40 with respect to X-axis 12 merely effects the coupling efficiency.
:::

WO 95/33219 r~ . c -'l7 11 21 9094~
FIGURES 3A and 3B illustrate a possible configuration for input focal plane 20 and output focal plane 42 in FIGU~E 2, respectively. Focal plane 20 i nrlllA~c six input images, A through F . Input images A
through F may be terminations for optical fibers. The inputs are arranged :~y L ically about Y-axis 14 and Z-axis 49, which would be out of the page in FIGI~RE 2.
Input A is shown at position 50, Input B at position 52, Input C at position 54, Input D at position 56, Input E
at position 58, and Input F at position 60. Shading has been used to differentiate the signals at each input.
FIGURE 3B shows the configuration for output focal plane 42 of FIGIIRE 2. As described in discussions related to FIGllRE 2, the images at input focal plane 20 have been inverted about Y-axis 14 and Z-axis 49 at output focal plane 42. In this manner, the outputs ~ ,~LL~jL ~ ing to the inputs of FIGURE 3A, designated the prime of the input, are imaged at output focal plane 42 at an opposite di6tance from Z-axis 49. Therefore, output focal plane 42 inrl~ C Output A' at position 62, Output B' at position 64, Output C' at position 66, output D' at position 68, Output E' at position 70, and output F' at position 72. It is noted that the shading of the inputs in FIGURE 3A has been carried over to the outputs of FIG~3RE 3B so that the COLL~ A1n~ output location for each input is easily identified. Therefore, Input A has the same s~ading as Output A', as do the other inputs and outputs for FIGURES 3A and 3B. Based on optical reciprocity, output focal plane 42 could be used as the input with input focal plane 20 forming the output .
FIGI RE 4 illustrates an: - ' i- L of the present inventive optical switch. Optical switch 74 i nrlllA~c a collimator or collimating lens 76 and a decollimator or A~coll il--ting lens 78. Input 84 is located on focal plane 82 of collimating lens 76. Output 90 is located on -wo 95/33219 ~ 17 12 21 909q4 focal plane 88 of lens 78. Reflector 92 i6 positioned between lens 76 and 78. Reflector 92 has first position 94 and second position 96, and may be ~ in a flat mirror . Ref lector 92 may be moved between positions 92 and 94 by actuator 97. Actuator 97 may comprise a piezo-electrical device that receives electrical control signal 99 that causes actuator 97 to move reflector 92 between the two positions. Noving reflector 92 between positions 94 and 96 changes the positions of outputs 90 between position 98 and 100, respectively. Several poqfiihl~
configurations for actuator 97 are described in ~.S.
Patent No. 5,221,987, entitled FTIR Modulator, ~issued to T.~ h 1 i n, the inventor of the present invention . U. S .
Patent No. 5,221,987 is expressly inCuL~oLclted by ref erence .
FIGURE 5 shows a possible configuration for input focal plane 82 using the input references from FIGURE 3A.
Input focal plane 82 in~ c Input A at position 50, Input C at position 54, Input D at position 56, and Input F at position 60. The inputs of input focal plane 82 are shown centered along Y-axis 14 and Z-axis 49 for reference ~uL~oses only, it being understood that the inputs need not be centered nor axially aligned. Input B
and E are not depicted for simplicity, but could be shown as in FIGURE 3A. With reflector 92 in first position 94, the inputs are centered about Z-axis 14 as shown in Figure 5. Moving reflector 92 to position 96 changes the centering of the inputs to virtual axis 102.
FIGURES 6A and 6B depict output focal plane 88 from FIGURE 4 when reflector 92 is in its first and second positions, respectively. The output references from FIGURE 3B shall be used in ~ cllCi n~ output focal plane 88. FIGURE 6A shows output focal plane 88 with reflector 92 in first position 94 with the outputs focused about Y-axis 14 and Z-axis 49. As previously described in connection with r~ i nn~ on FIGURE 2, input focal _, _ . _ . . _ . . . . _ .

W0 9S/332~9 r~ l~v~ ' c 'l7 ~ 13 ~l 9094~
plane 82 is reimaged to output focal plane 88 by lenses 7 6 and 7 8 with the inputs inverted and reimaged about Y-axis 14 and Z-axis 49. In this way, Input A at position 50 is reimaged at Output A' at position 62, Input C is reimaged at Output C' at position 66, Input D
is reimaged to Output D' at position 68, and Input F is reimaged to Output F' at position 72 in output focal plane 88.
Switching reflector 92 to second position 96 has the effect of rh;:ln~i n~ the virtual center of input focal plane 82 in FIGURE 5 to virtual centerline 102. A shift in the virtual center of input focal plane 82 causes a CUrL ~ ;n J shift when the input images are reimaged on output focal plane 88. With reflector 92 in second position 94, the outputs at output focal plane 88 are centered about Z-axis 49. Using the reimaging concepts previously described, Input A is reimaged to Output A' at position 62, Input C is reimaged to Output C' at position 64, Input D is reimaged to Output D' at position 68, and Input F is reimaged to output F' at position 70. The shading of inputs and outputs provides easy identif ication of the routing of the signals from input to output.
Switch 74 uses reflector 92 and the cu..~ L~ of optical signal spatial ~nro~lin~ and imaging lenses to switch input signals to a number of output signals by virtually shifting the centerlines of lenses 76 and 78.
The principal that an input image will be reimaged at an output in eSIual but opposite amounts about the centerline still applies, except that reimaging is done about a new virtual centerline. This allows for a shift in spatial position and also a re~-L all, L of the order of outputs when compared to the inputs. In this way, optical signals at input optical fibers terminated at input focal plane 84 may be routed to uu~ output optical fibers terminated at output focal plane 88. It is noted that w0 95/33219 E~ 17 reflector 92 for switch 74 i5 shown with two positions for illustrative purposes only. Reflector 92 may have numerous positions each providing a different virtual axis for the lenses without departing from the inventive concepts of the present invention.
FIGURF 7 shows an alternate DmhO~ of the present invention using a single lens. switch 106 i n~ DC lens 108 that both collimates and decollimates light beams. Focal plane 112 of lens 108 contains both the inputs and output signals for switch 106. The input signals to switch 106 are represented by point 116, and the output signals are re:~Las~---ed by point 118, it being understood that the number of input and output signals ~Ire not limited to the number shown in FIGURE 7. Switch 106 also ;nr~lllAD~ reflector 92 having first position 94 and second position 96, actuator 97, and return reflector 114. The input signals represented by point 116 ~rom focal plane 112 are collimated by lens 108 into collimated beams and reflected by reflector 92. The reflected collimated beams are directed to and reflected by return rei~lector 114. After reflection by return reflector 114, the collimated beams are again reflected by reflector 92. These signals are then decollimated by lens 108 to output signals represented in FIGURE 7 as point 118 in focal plane 112.
In one ~ of switch 106, return reflector 114 is at bias angle ~ 120 with respect to surface 122, that is per~Dn~iclll~r to focal plane 112. Bias angle 120 can be used to provide a fixed offset for the position of the input and output signals in focal plane 112. In this way, the input signals represented by point 116 are spatially displaced in focal plane 112 to provide the output signals represented by point 118.
FIGURES 8A and 8B show focal plane 112 of switch 106 with reflector 92 in first position 94 and second W0 95/3321g r~ 7 15 2 ~ 90944 position 96, respectively. FIGTlRE 8A shows a possible configuration for Pocal plane 112 having multiple input signals and multiple output signals and with reflector 92 in first positlon 94. The input signals are ~ as~l.l.ed by Input A, Input B, and Input C, while the outputs are represented by Output A', Output B', and Output C'. In the eYample of FIGURE 8A with reflector 92 in first position 94, the input and output signals are centered about Y-axis 14 and Z-axis 49. In this way, Input A at position 124 is reimaged to Output A' at position 126, and Input B at position 128 is reimaged to Output B' at position 130. In this example, Input C and Output C' are shown inactive for the first position for reflector 92.
(The position of Output C' if Input C were active is shown in FIGllRE 8A for reference purposes only. ) Like shading on the associated inputs and outputs is provided for clarity.
Continuing the example of FIGURE 8A, FIGT)RE 8B shows the results when reflector 92 is moved to second position 96, causing focal plane 112 to shift to a virtual center about Y-axis 104. In this way, Input A is reimaged to Output A' at position 132, Input B at position 128 is reimaged to B' at position 130, and Input C at position 134 is reimaged to Output C' at position 136. By the process of optical reciprocity, the outputs of switch 106 can be the inputs and the inputs can be the outputs.
FIGURE 9 illustrates an alternate f ` a;~ t for optical switch 106 of FIGURE 7 . Switch 138 ; ~ A~:
reflector 92 with positions 94 and 96 and eliminate6 the need for return reflector 114. Input signal6 from focal plane 112 re~Las~l-l ed by point 116 are collimated by lens 108. The collimated beams are reflected by reflector 92 and ~ ~ ol 1 ir-ted and focused by lens 108 to output signals represented by point 118 on focal plane 112. By moving reflector 92 between positions 94 and 96 with actuator 97, the virtual center oP the inputs at point 116 and the outputs at point 118 can be modified for switching the inputs to outputs as shown and de6cribed in cllc~ nc relating to FIGURES 7 and FIGURES 8A and 8B.
It is noted that while shifts in a signal ' 8 path have been ~; cc~cced in association with shifts about a single axis, that the6e shifts can take place a~out any or multiple axis without departing from the inventive concepts of the present invention.
FIGURES 10A-lOC show an alternate ~ ' ' i L of the present switch configured to form a reversing bypass switch. FIGURE 10A represents the function performed by reversing bypass switch 140. In the first position of switch 140, Input A couples to Output A' and Input B
couples to Output B'. In the second position, Input A
couples to Input B and Output A' couples to Output B'.
Using, for example, switch 106 of FIGURE 7, or switch 138 of FIGURE 9, reversing bypass switch 140 may be provided using the CO~IC~ytS of the present invention.
Switch 106 of FIGURE 7 may be configured to form reversing bypass switch 140 of FIGURE 10A. By r~-plAci lens 108 with an t~J~L-J~ iate lens, such as a gradient index tGRIN) lens, allows 6witch 106 to provide a reversing bypass function.
FIGURE 10B shows the focal plane associated with GRIN lens 141 that replaces lens 108 of switch 106 to form reversing bypass switch 140. By coupling optical fibers for feedback directly to the focal plane of GRIN
lens 141, as 6hown in FIGURE 10B, reversing bypass may be achieved. Optical fibers 142 may be coupled to lens 141 by an ~.~yr~Liate index matching adhesive to m;n;m; ze energy 1088 or refraction as an optical signal goes from fiber 142 to lens 141. Optical flbers 142 provide Input A at position 144, Input B at position 146, output A' at position 148, and Output B' at position 150. Return loop 152 provides a return path between positions 154 and 156, and may also be : '; ed in an optical f iber .

WO 95/33219 PCTIUS95~0651~
17 2 ~ 9r~944 With reflector 92 of switch 106 of FIGURE 7 in first position 94, focal plane 112, as depicted in FIGURE 10B, iB centered about Y-axis 14 and Z-axis 49. As previously described, Input A at position 144 is imaged to Output A' at position 148, and Input B at position 146 i-- imaged to Output B' at position 150. In this way, Input .~ is routed to Output A ' and Input B is routed to Output B ' as shown in FIGURE lOA.
FIGURE 10C shows the resulting shift in the virtual axis of focal plane 112 of lens 141 to Y-axis 104 and Z-axis 49 when reflector 92 of switch 106 is moved to second position 96. Input A at position 144 is imaged to the input of return loop 152 at position 154. Return loop 152 provides Input A to position 156 of return loop 1'~, that, in turn, is reimaged to Input 8 at position 146. Output A' at position 148 is reimaged to Output B' at position 150. In this way, Input A is routed to Input B and Output A' is routed to Output B' providing the second position of reversing bypass switch 140 of FIGURE
lOA.
In a similar manner, switch 138 of FIGURE 9 can be modified to provide reversing bypass switch 140.
FIGURES 11A through llD show an . ' - ' i r Z. of the present invention conf igured to f orm cros6-bar switch 158. In its first position, Input A couples to Output A' and Input B couples to Output B'. In the second position of switch 158, Input A couples to Output B ' and Input B
couples to Output A'.
Optical switch 74 of FIGURE 4 may be conf igured to form cross-bar switch 158. For switch 74, using an ~L~,~Liate lens such as a GRIN lens for lens 76 an~ 78 allows switch 74 to provide the cross-bar function. Lens 76 may be ~ ';ed in GRIN lens 159, and lens 78 may be cl in GRIN lens 160. FIGURE llB shows input focal plane 163 associated with GRIN lens 159. Fibers 142 are coupled directly to focal plane 163 of GRIN lens 159 as WO 95/33219 P~ J,.,'.'C''17 previously described in connection with rl;cCIlc~irmc of FIGURES lOB and lOC. Input focal plane 163 includes Input A at position 161, Input B at position 162, Output A' at position 164, and Output B' at position 166.
FIGURE llC shows the fiber configuration at focal plane 165 of second lens GRIN 160, ;nrl~ ;n~ first return loop 170 coupling positions 172 and 174, second return loop 176 coupling positions 178 and 180, third return loop 182 rollrl ;nrj positions 184 and 186, and fourth return loop 188 co~l;n~ position 190 and position 192.
The return loops may be . ~ '; ed in optical f ibers and may be coupled to focal plane 165 associated with lens 160 by an index matching adhesive as previously described .
With reflector 92 in first position 94, the input signals from lens 159 are imaged at line 194 in focal plane 165 associated with lens 160. In this way, Input A
at position 161 is imaged to position 192 on fourth return loop 188. Loop 188 provides Input A to position 190 which, in turn, is reimaged to position 164 at Output A'. Input B at position 162 i5 imaged to position 184 on third return loop 182. Loop 182 provides Input B to position 186 which, in turn, is reimaged to position 166 at Output B'. In this first position, therefore, Input A
is coupled to Output A' and Input B is coupled to Output B' .
Noving reflector 92 to second position 96 causes the input signals from lens 159 to be imaged at line 196 on focal plane 165 of lens 161. FIGURE llD shows focal plane 82 with return lens 160 focused about line 196.
Input A at position 161 is imaged to position 180 of second return loop 176. Loop 176 provides Input A to position 178 which, in turn, is reimaged to position 166 at Output B'. Input B at position 162 is imaged to position 172 of ~irst return loop 170. Loop 170 provides Input B to position 174 which, in turn, is rei~aged to WO 95/33219 r~ .C r17 position 164 at output A'. In this manner, Input A is coupled to Output B' and Input B i5 coupled to Output A'.
C~ ~ 55 b~r switch 158 may be accomplished by looping return fibers from focal plane 165 of len5 160 to focal plane 163 of lens 159. An example of a configuration of the present invention utilizing return fiber between lenses will be described in diccllcc;onC related to FIGURES 19-19C below.
The present invention a5 de5cribed in tli CCllccinnc on FIGURES 4-llD accomplishes 5witching optical signals between input fibers and output fibers through shifting one or more virtual axis of the system by ~hiln~i n~ the position of a ref lector between multiple positions .
Shifting the virtual axis of an image can also be accomplished by the concept of rLu-L- c.ted total internal reflection (FTIR).
When light travels from a denser medium, such as glass, into a less dense medium, such as air, the angle of the light in the less dense medium is greater than when in the denser medium. Total internal reflection is the } ~r whereby light traveling at an angle in the denser medium will be perfectly reflected by the interface between the denser and less dense medium. This perfect reflection or total internal reflection may be Llu:,~L~ted by bringing a second refractor into proximal contact with the ref lecting surf ace of the denser medium.
The term "proximal contact" will be further def ined in rl; ccl~cc~ nnc related to FIGURE 18 . ~he light traveling in the denser medium will pass through the reflecting surface and travel into the second refractor. This is the concept of frustrated total internal reflection ( FTIR) .
FTIR is described in U.S. Patent No. 5,221,987. The present invention employing FTIR routes the optical energy from one or more input fibers to a plurality of output f ibers . The switch routes the energy by W0 95133219 2 ~ 9 0 9 4 4 r~ s c - 17 frustrating the total internal reflection in the switch by a variable but controlled amount.
FIGURE 12 illustrates an ~nho~ L of the present optical switch utilizing FTIR. FTIR optical switch 200 ; nrl~ collimator 76 and decollimator 78 that may be lenses. switch 200 ;nr~ DR refractor 202 positioned between lenses 76 and 78. Refractor 202 is a right angle prism in the ~ '; L of 6witch 200 of FIGURE 12, it being understood that other configurations for refractor 202 may be suitable for switch 200 without deviating from the inventive concepts of the present inventions. switch 200 also ;nrl~ R a second refractor or switchplate 204 that is used to ~Lu:~Late total internal reflection in refractor 202. Switch 200 also ;nrll~ s actuator 205 for moving switchplate 204 into proximal contact with refractor 202. In one ~mho~;r- ~ of switch 200, actuator 205 is a piezo-electrical device. Configurations for actuator 205 may be found in U.S. Patent No. 5,221, 987.
Input signals are provided to switch 200 by input fiber 210 located in the focal plane for lens 76, and output signals are provided to output fibers 212 and 214 located at the focal plane for lens 78.
In the first position of switch 200, switchplate 204 does not touch refractor 202. The energy from input fiber 210 is collimated into beam 216 by collimating lens 76 and beam 216 is introduced into refractor 202.
Collimated input beam 216 is reflected at reflecting surface 218 of refractor 202 by total internal reflection tTIR) and forms primary collimated output beam 220.
Primary collimated output beam 220 is focused by decoll ;r-ting output lens 78 and to first output optical f iber 212 .
To accomplish switching from input optical fiber 210 to second output optical fiber 214, switchplate 204 is brought into proximal contact with reflecting surface 218 of refrActor 202 by actuator 205. This rLu~,LLaLes the W095133219 r~l"~,, 5.

total internal reflection in refractor 202 resulting in input collimated beam 216 being transmitted into switchplate 204. Collimated beam 216 is reflected from reflective surface 222 of switchplate 204 by total internal reflection as 5~r~nnrl:~ry collimated output beam 226. It is noted that total internal reflection at reflective surface 222 is not always n~ cc~ry.
Reflective surface 222 of switchplate 204 is at a bias angle ~ 223 to inside surface 224 of switchplate 204. 5~c-~n~ ry collimated output beam 226 leaves refractor 202 at an angle of two times angle 223 ~ to that of primary collimated output beam 220. Secondary collimated output beam 226 is then reimaged by output lens 78 onto second output optical fiber 214. By this method, an optical signal at input optical fiber 210 can be switched between output optical fibers 212 and 214 by moving switchplate 204 into and out of proximal contact with refractor 202. When switchplate 204 is not in proximal contact with refractor 202, the optical signal from input optical fiber 210 is imaged to first output optical fiber 212. When switchplate 204 is brought into proximal contact with refractor 202, total internal reflection in refractor 202 is LLUa~LClted, thereby causing the optical signal from input optical fiber 210 to be imaged to second output optical fiber 214.
Controlling the spacing between switchplate 204 and refractor 202 controls the rLuaLL.lt.ion of the total internal reflection by refractor 202. The reflections at reflective surface 218 when LLu:.~L.lted by surface 224 are developed from field theory and have been well defined.

WO 95/33219 r~ r rl7 22 2 ~ 90944 The reflection at reflective surface 218 of refractor 202 of switchplate 204 is defined as:
R = 1 - l~La ~ sillh(y)2 + P] (2, y = 2*~*nl*(d/A)~[(nO/nl)2*sin(02 - I]-l12 (3 a,= [(nO/nl)2 - 1]*[(n2/nO)2*(nO/nl)2 - 1]

4(nO/nl) cos(O[(nO/nI)2sin(q~)2 - I]~[(n2/nO)2 - sin(q~)2]~V2 (4) a~ = a,l[(nO/nI)2 + l]*s~ )2 - l}2 (S) {[(n2/no)2 S~n(O2]-v2 + (n2lnO)2cos(~) 4(n2/nO)2cos(0[(n2/n~)2 - sin(qb)l]~ll2 {[(n2/nC)2 - si~(O2]v2 + (n2/no)2cos(~l~)J2 4(n2/nO)2cos(~))[(n2/nO)2 - SiD((1))2]-l12 where: The sub~cripts, 6 and p, refer to waves polarized perp~n~l1c~ r to and parallel to the plane of inr~ nce~
respectively .
= the angle from the normal in refractor 202 at reflective surface 218;
nO = the index of refraction of refractor 202.
nl = the index of refraction for the medium between refractor 202 and switchplate 204.
n2 = the index of refraction of E;witchplate 204.

wo 95/33219 ~ Jr~IC ~'l7 2 1 90q44 FIGURE 18 illustrates the ref lection at ref lective surface 218 of refractor 204 as a function of the spacing between surface 218 and sUrface 224 for several typical angle5 to be encountered at surface 222 and as a function of the spacing between refractor 202 and switchplate 204.
FIGURE 18 d L c.tes that the degree of rLU15Ll~tiOn of the total internal reflection within refractor 202 is a function of the spacing between refractor 202 and switchplate 204. Therefore, by bringing switchplate 204 into proximal contact with refractor 202 (as defined by Equations (2) through (7) and FIGURE 18) controls the portion of the collimated beam that is reflected by refractor 202 and the portion reflected by switchplate 204 .
Alternatively, by varying the spacing between refractor 202 and switchplate 204, an input optical signal from input optical fiber 210 may be variably split between output optical fibers 212 and 214 forming a ~iignal sp}itter. In a similar manner, switch 200 may be used to variably attenuate an input signal to either output optical fibers 212 and 214.
In the preferred ~ t, lenses 76 and 78 are GRIN lenses. Input optical cable 210 may be coupled directly to lens 76 and output optical cables 210 and 214 may be coupled directly to len8 78 by the ~chniq previously identified when using GRIN lenses.
The operation of switch 200 haF been described as having an unswitched position with :iwitchplate 204 removed from ref~ LuL 202 and a switched position when switchplate 204 is brought into proximal contact with leL. ~.~.L~I 202. With this configuration, switch 200 does not employ FTIR in reflector 202 when unswitched and does when switched. It is noted that the operation of switch 200 can be L-:v~ ed without departing from the inventive 3 5 ~ of the present invention . For example, the unswitched condition for switch 200 can be est~hl i l::h~l to _ _ _ _ ~

WO 95/33219 I~ l~,S.i` 17 2 ~ 9(J944 be when switchplate 204 is in proximal contact with refractor 202 causing FTIR and the switched condition of switch 200 would be when switchplate 204 is removed from refractor 202 and FTIR in refractor 202 does not occur.
The choice of switched and unswitched conditions for switch 200 does not affect its performance.
Additionally, actuator 205 of switch 200 has been thus far described as moving switchplate 204 into and out of proximal contact with refractor 202. Actuator 205 may be : ` - ' i ed in any of the trRn~ P~s described in U. S .
Patent No. 5,221,987 without departing from the inventive concepts of the present invention. Actuator 205 can be used to move switchplate into and out of proximal contact with refractor 202 ~lPpPn~ing on the configuration of the optical switch. In this way, actuator 205 controls the spacing between refractor 202 and switchplate 204.
FIGURE 13A shows an alternate : -'; L of the present invention using FTIR to switch a single input optical fiber to multiple output optical fibers. Switch 228 inrl~ Ps collimating lens 76 and decollimating lens 78. The input to switch 228 is provided by input optical fiber 210 and the output is provided by output optical fibers 212 and 214 6hown, and fibers 230 and 232 hidden in the view of FIGURE 13A (see FIGURE 13B). Switch 228 ~nrll-AP~ refractor 234 in the form of back to back prisms or a rhomboid. Refractor 234 has first reflective surface 218 and second reflective surface 236. Switch 228 has two switchplates, i nr~ n~ switchplate 204 and switchplate 237, and two actuators, ;n~ nq actuator 205 and actuator 233.
The operation of switch 228 of FIGURE 13A is similar to that described for switch 200 of FIGURE 12. By bringing switchplate 204 into contact with first reflective surface 218 of refractor 234, total internal reflection at first reflective surface 218 within refractor 234 is LL- ~LLc.ted, so that the optical signal WO 95/33219 ~ 5~l~
; 25 2 1 90944 traveling in re~ractor 234 is shifted, as previously described in rl i RCllq,q; nnC of FIGURE 12 . In a similar mannerr bringing switchplate 237 into contact with second reflective surface 236 of refractor 234, r-u~LLaLes total internal reflection in refractor 234 shifting the optical signal traveling at second reflecting surface 236 in refractor 234. once total internal reflection is rLu~L~ted at second reflecting surface 236, the optical signal in refractor 234 will travel through inside surface 238 of switchplate 236 to reflective surface 239 where the signal is reflected. Switchplate 237 may also have a bias angle (not explicitly shown) similar bias angle ~ 223 on switchplate 205. The bias angle on switchplate 237 may be in the same plane as bias angle 223 on switchplate 205. In the preferred ~ L, however, the bias angle on switchplate 237 is perpen~;cl~lAr to bias angle 9 223, and, therefore, into the page. By this technique, switchplate 204 provides two positions for the optical signal traveling in r~fractor 234, and switchplate 237 provides two positions for the optical signal traveling in refractor 234. This allows an input beam from input optical fiber 210 to be switched to four output optical fibers. A poq~qihle configuration for the four output optical fibers 212, 214, 230, and 232 is shown in FIGURE 13B.
It is noted that optical switches 200 and 228 shown in FIG~RES 12 and 13A, respectively, may be C~qrA~le~, and that each cascade provides additional signal routing positions. In this way, an optical signal at input optical fiber 210 may be switched to any one of numerou6 output optical fibers. It i5 also noted that the nu~ber of switches incuL~L~lting the present invention that may be c~qc~ d is not limited to the c 'i- Ls shown.
FIG~RE 14A illustrates another ~mhorl i - t of the 35 present invention. Switch 241 of FIGI~RE 14A is similar W0 95/33219 ~ 7 to switch 106 of FIGURE 7 and includes refractor 202, switchplate 204 and actuator 205 similar to switch 200 of FIGURE 12. Switch 241 also employs collimating and ~ocoll ;rqting lens 242. An input optical signal is provided to switch 241 by input optical fiber 210, and the output signal is provided to output optical f ibers 212 and 214. Similar to optical switch 106 of FIGURE 7, switch 241 uses return reflector 114 shown displaced from refractor 202. Return reflector 114 may also have bias angle ~ 120 with respect to perpon~l;c~ qr surface 122.
It is noted that return ref lector 114 may be ~ho~l i ed in refractor 202 without departing from the inventive ~Ls of the present invention.
Input optical fiber 210 provides an image to lens 242, which, in turn, provides collimated input beam 216 to refractor 202. With switchplate 208 removed from reflecting surface 218 of refractor 202, collimated beam 216 reflects from surface 218 by total internal ref lection and travels to return ref lector 114 . Bias angle 120 of return reflector 114 causes a shift in the return beam (not explicitly shown). The return beam is then again reflected by reflecting surface 218 and travels back to lens 242a that ~locol 1 ;rotes and focuses the return beam to first output optical fiber 212. Lens 242a is shown off6et from lens 242 for illustrative purposes only. Lens 242a may be lens 242 that both collimates the input image and l~col 1 ;r-tes the return optical signal. For some applications of the present invention, it may be desirable to have separate collimating lens 242 and separate tl~oroll ir-ting lens 242a.
To switch the output from output optical fiber 212 to output optical fiber 214, switchplate 204 is brought lnto contact with reflecting surface 218 of refractor 202 . This rL-,~L- ~Ites the total reflection in refractor WO 95/33219 ~ c--17 27 21909~4 202 and causes beam 216 to reflect from reflecting surface 222 of switchplate 204. As described in li;cc~lcFir~nc for FIGURE 12, this causes a shift in the return beam that is focused by lens 242a to output optical fiber 214.
In this way, an input signal may be switched between two or more output fibers with a single lens. This eliminates the need and expense of a second lens making switch 241 less expensive.
FIGURE 15 shows another ~mho~l; L of the present invention conf igured as a reversing bypass switch .
Switch 244 of FIGURE 15 is similar to switches 200 and 241 of FIGURES 12 and 14A, respectively. Switch 244 ~nrlll~sPc refractor 246 in a right angle prism ~mho~l;r ~.
Refractor 246 has reflective surface 248 for providing a return beam. Switch 244 has lens 250 which both provides the input signals and receives the output signals. Lens 250 may be a GRIN lens having fibers coupled the}~eto as previously described in c~nn~ctinn with the fl;Rcllcfiicmc on FIGURES lOB and lOC. Switch 244 has switchplate 252 which is similar to the previously identified switchplates and an actuator (not explicitly shown) for moving switchplate 252. Reflecting surface 248 of refractor 246 may have a slight bias angle in order to provide a fixed offset in the return beam when routing an optical signal between input and output.
In operation of switch 244 of FIGURE 15, input signals are collimated by lens 250 and the collimated signals reflect by total internal reflection at reflective surface 218 to reflective surface 248. A bias on reflective surface 248 will cause a fixed offset in the collimated signals that are L~ .,ed to reflective surface 218 and on back to lens 250. Details on the operation of switch 244 will be described in Cc~nn~ct; r~n with FIGURES lOB and lOC. When switchplate 252 is not in contact with surface 218 of refractor 246, Inpu~ A at wo ssn32ls P~ ,. ''17 position 144 is routed to Output A' at position 148, and Input B at position 146 is routed to Output B' at position 150 as depicted in FIGURE lOB. Bringing switchplate 252 into contact with reflecting surface 218 of refractor 246 frustrates total internal reflection in refractor 246 causing a shift in the output beam as previously described and depicted in FIGURE lOC. In this way, Input A at position 144 is imaged to the input of return loop 152 at position 154. Return loop 152 provides the image to position 156, that, in turn, is reimaged to Input B at position 142. Output A' at position 148 is imaged to Output B' at position 150. In this way, Input A is coupled to Input B and Output A' is coupled to Output B' forming the second po6ition for reversing bypa6s switch 140.
FIGURE 16 depicts another ~n~ho~l i L of the present invention configured as a cross-bar switch. Switch 254 of FIGURE 16 is very similar to switches 200 and 241 of FIGURES 12 and 14A, respectively, and provides a cross-bar function as previously described in connection with cll~s;rn/: of FIGURES llA--llD. Switch 254 ;n refractor 246, switchplate 252, an actuator (not explicitly shown), and lenses 256 and 258. Lens 256 of swltch 254 may be configured similar to lens 82 of FIGURES llB and llD, and lens 258 may be configured similar to lens 160 of FIGURE llC. Lenses 256 and 258 may be ~ 1 in GRIN lenses as previously described.
In operation of switch 254, input optical signals are provided by lens 256 to refractor 246. These signals are reflected by reflecting surface 218 to lens 258.
1ens 258 ref lects the signals by employing return loops as previously described for lens 160. The reflected signals are also reflected by reflective surface 218 and back to lens 256. Additional details on the operation of switch 254 of FIGURE 16 will be described using FIGURES
llB-llD. When switchplate 252 i8 not in contact with .: .___ _ ____ . = . .. .: . ...

WO 95/33219 r~,~ 7 2 ~ 93944 surface 218 of refractor 246, Input A at position 161 is imaged to position 192 of fourth return loop 188. Return loop 188 provides the image to position 190, which, in tu3 ~is reimaged to Output A' at position 164. Input 8 at p~sition 162 is imaged to position 184 of third return loop 182 that provide6 this image to position 186. The image at position 186 is then reimaged to Output B' at position 166. In this way, Input A is coupled to Output A' and Input B is coupled to Output B'.
In order to accomplish cross-bar switching, switch-plate 252 may be brought into contact with surface 218 of refractor 248. This rLU~LL~lLeS total ;nto~n;~l reflection in refractor 246 causing a shift in the image as previously described. Input A at position 161 is then imaged to position 180 of second return loop 176. Loop 176 provides the image to position 178, which, in turn, i5 reimaged to Output B' at position 166. In a similar manner, Input B at position 162 is imaged to position 172 of first return loop 170. Loop 170 provides the image to position 174, which, in turn, is reimaged to Output A' at position 164. In this manner, Input A is coupled to output B' and Input B is coupled to Output A' forming the second position of cross-bar switch 158.
FIGURE 17 shows another ~ of the present invention providing a multiposition switch. Switch 260 tn~ A.og re~ractor 246 having total internal reflecting surfaces 262, 264, and reflective surface 266. Switch 260 also ;nnll--lD~ switch plates 268 and 270. The input and output to switch 260 i6 provided by lens 272 at surface 266 of refractor 246. An input signal provided ffl lens 272 will be reflected in refractor 246 by FTIR
surfaces 262, 264, and reflective surface 266. Providing a bias angle (not explicitly shown) on surface 266 will cause a shifting of the signal as an output at lens 272.
Tn~ l_.. Lly moving switchplates 268 an 270 into contact with refractor 246 can accomplish switching of optical WO 95133219 1 ~ 17 signals provided by lens 272 as previously described for switches 200, 228, 241, 244, and 254. It should be rPro~n; ~sd that the reflective surface 266 can be replaced with an output lens, and that refractor 246 may be r~cc~lflP~l to provide ~ ded switching.
FIGURE 20 shows switching system 276 employing switch array 278. Individual switches 280 of array 278 may be: ~ ~iPC9 in the present invention for switching optical signals. To further describe system 278, first stage 282 will be referred to as the input and second stage 284 of array 278 will be referred to as the output, it being understood that signals may travel in both directions in system 276. Each switch 280 in stage 282 includes multiple inputs 286 which may be optical fibers.
Each switch 280 in stage 282 is coupled to individual switches 280 of second stage 284 by int~ i Ate couplings 288 . Int~ te collr~ i n~C 288 may also be ~mhorliPtl in optical fibers. Each switch 280 of second stage 284 provides output optical 6ignals 290, which may also be ~ d;ed in optical fibers. It is noted that the number of input 286, output 290, and int~ ';Ate 288 collrl; n~C need not be limited to the number shown in FIGURE 18.
In operation of system 276, each switch 280 of first stage 282 6witches an input signal to the appropriate int~ ';Ate coupling 288. The signal on the int~ te coupling is then switched by one of the individual switches 280 in second stage 284 to an ~I~Lopliate output. Each switch 280 receives control signal 292 from controller 294. Controller 294 sets the position of each switch by triggering the actuator in each switch so that optical signals are routed between inputs and outputs in the appropriate path. Switching system 276 of FIGURE 20 shows that the present invention can be used to build a multistage switching system for prsCQe:c:; n~ optical signals .

WO 95J3321~ F~, ' 2 ~ S.'C 17 FIGURES l9A-19C illustrate a 4x4 cross-bar switch that may be implemented using the concepts of the present invention. In a cross-bar switch, each of four inputs can be routed to each of four outputs. Switch 300 of FIGURE l9A-19C can be implemented using any two lens L of the present invention previously ~ C~lec~
Switch 228 of FIGURE 13A is one ~ ` a;_ L of the present invention that may be used to; l~ L cross-bar switch 300 of FIGURE l9A-19C. Switch 300 requires a switch that has two lenses and two switchplates in order to achieve switching four inputs to any one of four outputs.
FIGURE l9B represents a possible conf iguration f or the input focal plane associated with lens 76 in FIGURE 13A. In the preferred ~ ' ;r L, lens 76 is GRIN
lens 301 having associated focal plan 302. The inputs at focal plane 302 are designated as Input A at position 304, Input B at position 306, Input C at position 308, and Input D at position 310. Each of these inputs may be provided to focal plane 302 of lens 301 by, for example, an optical fiber. The optical fiber may be attached to lens 301 by an à~Lu~Liate index matching adhesive as has been previously described for coupling optical fibers to a GRIN lens.
FIGURE l9C L~Lase,lL~ the configuration for the output focal plane associated with lens 78 in FIGURE 13A.
In the preferred ' -';- L, lens 78 is GRIN lens 311 having focal plane 312. output focal plane 312 of lens 311 ;nrlllA-~c output A' at position 314, Output B' at position 316, Output C' at position 318, and ûutput D' at position 320. Each of the output locations on lens 311 has an optical fiber a~Lv~Liately coupled to it.
FIGURE l9A represents the relati~n~h;rs between input focal plane 302 and output focal plane 312 for cross-bar switch 300. To achieve the combinations of the signals in switch 300, return loops a 314, b 316, and c 318 are required. Each of the return loops will route a wo 95/33~19 P~lll). C ~17 signal received at output focal plane 312 back to input focal plane 302 50 that operation of cross-bar switch 300 may be achieved.
Returning to FIGURES l9B and l9C, a configuration for the orientation of the return loops with the inputs and outputs i8 shown. On input focal plane 302, return loop a 314 is at position 320, return loop b 316 is at position 322, and return loop c 318 is at position 324.
The corr~spo~l;n~ configuration for the return loops in output focal plane 312 are shown in FIG~RE 19C. Return loop a 314 is at position 326, return loop b 316 is at position 328, and return loop c 318 is at position 330.
FIGURE l9A also ~1 L. ,- Les how the imaging o~
signals within cross-bar switch 300 occurs. Vertical axis 332 is provided as a reference between the location of the inputs on input focal plane 302 and the outputs on output focal plane 312. Matrix 334 has been superimposed on switch 300 to aid in explaining the routing of signals rrom input focal plane 302 to output focal plane 312.
Row 336 represents the condition of switch 300. As previously noted, switch 300 may be implemented with two switchplates. The condition of the switchplates is ~L~5~ ed by the pair of numbers in row 336. For example, the condition 0,0 ~ e~el.ts switch 300 with both switchplates open, with open being set arbitrarily with switchplate in proximal contact with the refractor, it being understood that open could be set for when the switchplate is not in proximal contact with the refractor. Therefore, for example, in column 338, the designation 0,0 refers to both switches as open, and in column 340, 1,0 refers to the first switchplate closed and the second switch open. The L~ ; ni n~ columns of matrix 334 are self explanatory.
ThQ horizontal lines in matrix 334 illustrate the virtual axis for the signals ~or the switch for the four switch positions of row 336. Axis 342 is the virtual _ _ , . . _ _ .

W09~33219 r~ c-- 7 axis ~or the switch in 0, 0 state, virtual axis 344 is the virtual axis for the switch in state 1,0, virtual axis 346 is the virtual axis for the switch in state 0,1, and virtual axis 348 is the virtual axis for the switch in state 1,1.
The entries within matrix 334 re~L~s~l.L the position on output focal plane 312 that the inputs from input i~ocal plane 302 are imaged to. For example, for switch state 0, 0, Input A at position 304 is aligned with virtual axis 342 50 it is not displaced about virtual axis 342, and is aligned with position 316 on output focal plane 312. Input A, therefore, couples to output B' at position 316. Input B at position 306 is imaged about virtual axis 342 to position 314, and, therefore, couples to Output A'. Input C at position 308 is imaged about virtual axis 342 to position 326 to return loop a 314. Return loop a 314 provides this signal back to position 320 of input ~ocal plane 302.
Return loop a at position 320 is imaged about virtual axis 342 to position 318 on output focal plane 312 and eouples position 320 to Output C'. Therefore, Input C
eouples to Output D'. The entry "aC" at position 341 in matrix 334 indieates that Input C is provided to position 320 by return loop a 314. Input D at position 310 is imaged about virtual axis 342 to position 328 at the input of return loop b 316. Return loop b 316 provides the signal back to input focal plane 302 at position 322.
Position 322 is then reimaged about virtual axis 342 to position 318 at Output C' of output ~ocal plane 312.
Therefore, Input D eouples to Output C'. In this way, with switch 300 in state 0,0, each input is coupled to a dif f erent output .
Matrix 334 helps understand how the inputs ~rom input focal plane 302 are imaged to the outputs on output focal plane 312. In a similar manner, the other states of switch 300 can be tracked using matrix 334 50 that W09S/3321~ P~l/u. _C~r~7 34 2 ~ 90944 each input may be switched to a different output without blork; ng .
Switch 300 of FIGURE l9A-19C provides a te~hnic advantage of a ~:L~,ss-bar switch using the present invention. Switch 300 may also be put into an array of switches to provide, for example, a 16x16 non-blocking cro6s-bar switching of signals.
It is noted that the present invention may have ~,us applications, ;n~ ;n~, but not limited to:
laser Q-switching applications, as a laser safety device, and as an electric chopper wheel. Addltionally, the present invention may provide switching of RF signals.
By using larger scale materials that are LLU.-2,~al~:..t to RF signals, advantages of the present invention may be achieved for procPf ~in~ RF signals.
The present invention for routing optical signals provides t~-hn;rAl advantages of low cost and fast switching speeds. The present invention may use a common mirror or the concept of IL-l~LL~lted total internal reflection to achieve shifts in a virtual focal plane of an image. In this way, an optical signal can be switched, attenuated, modulated or split between variou6 outputs .
Although the present invention has been described in detail, it should be understood that various changes, ~iubstitutions and alterations can be made hereto without departing from the spirit and scope of the invention as def ined by the ~ claims .
.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for switching an input optical signal to one of a plurality of output optical locations, the apparatus comprising:
a lens for collimating the input optical signal into a collimated beam; and a reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

2. The apparatus of Claim 1 further comprising a decollimating lens for decollimating and focusing the collimated beam.

3. The apparatus of Claim 1 wherein the lens is further operable to decollimate and focus the collimated beam.

4. The apparatus of Claim 1 wherein the lens comprises a GRIN lens.

5. The apparatus of Claim 2 wherein the decollimating lens comprises a GRIN lens.

6. The apparatus of Claim 1 wherein the reflector comprises a mirror.

7. The apparatus of Claim 1 further comprising an actuator responsive to a control signal for moving the reflector between the plurality of positions.

8. The apparatus of Claim 7 wherein the actuator comprises a piezo-electrical device.

9. An apparatus for switching an input optical signal to one of a plurality of output optical locations, the apparatus comprising:
a lens for collimating the input optical signal into a collimated beam; and a reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations, wherein the reflector further comprises;
a first refractor having a first reflective surface for reflecting the collimated beam by total internal reflection, a second refractor having a contact surface and a reflective surface, wherein the second refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the first refractor's first reflective surface when the second refractor is in proximal contact with the first refractor and so that the collimated beam enters the second refractor, and wherein the second refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

10. The apparatus of Claim 9 further comprising an actuator responsive to a control signal operable to control spacing between the first and second refractors.

11. The apparatus of Claim 9 further comprising a decollimating lens for decollimating and focusing the collimated beam.

12. The apparatus of Claim 9 wherein the first refractor is a prism.

13. The apparatus of Claim 10 wherein the actuator comprises a piezo-electrical device.

14. The apparatus of Claim 10 wherein the actuator adjusts the spacing between the first and second refractor by a varied and controlled amount so that a first portion of the collimated beam is reflected by the first refractor's reflective surface and a second portion of the collimated beam is reflected by the second refractor's reflective surface.

15. The apparatus of Claim 9 further comprising:
a third refractor having a contact surface and a reflective surface;
wherein the first refractor further comprises a second reflective surface for reflecting the collimated beam by total internal reflection after reflection by one of the first refractor's first reflective surface and the second refractor's reflective surface;
wherein the third refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the first refractor's second reflective surface when the third refractor is in proximal contact with the first refractor and so the collimated beam enters the third refractor; and wherein the third refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

16. The apparatus of Claim 15 further comprising a second actuator responsive to a control signal operable to control the spacing between the first and third refractors.

17. The apparatus of Claim 16 wherein the second actuator comprises a piezo-electrical device.

18. The apparatus of Claim 9 further comprising:
a third refractor having a first reflective surface for reflecting the collimated beam by total internal reflection after reflection by one of the first refractor's first reflective surface and the second refractor's reflective surface;
a fourth refractor having a contact surface and a reflective surface;
wherein the fourth refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the third refractor's first reflective surface when the fourth refractor is in proximal contact with the third refractor and so that the collimated beam enters the fourth refractor; and wherein the fourth refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

19. An apparatus for switching an input optical signal to one of a plurality of output optical locations, the apparatus comprising:
a lens for collimating the input optical signal into a collimated beam;
a first reflector for reflecting the collimated beam; and a second reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of the collimated beam by a selected amount in order to direct the collimated beam to a different one of the output optical locations.

20. The apparatus of Claim 19 wherein the lens is further operable to decollimate and focus the collimated beam after reflection by the first and second reflectors.

21. The apparatus of Claim 19 wherein the lens comprises a GRIN lens.

22. The apparatus of Claim 19 wherein the first and second reflectors comprise mirrors.

23. The apparatus of Claim 19 further comprising an actuator responsive to a control signal for moving the second reflector between the plurality of positions.

24. The apparatus of Claim 23 wherein the actuator comprises a piezo-electrical device.

25. An apparatus for switching an input optical signal to one of a plurality of output optical locations, the apparatus comprising:
a lens for collimating the input optical signal into a collimated beam;
a first reflector for reflecting the collimated beam;
a second reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of the collimated beam by a selected amount in order to direct the collimated beam to a different one of the output optical locations, wherein the first and second reflectors are embodied in a first refractor having a first reflective surface for reflecting the collimated beam by total internal reflection and a second reflective surface for reflecting the collimated beam;
a second refractor having a contact surface and a reflective surface;
wherein the second refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the first refractor's reflective surface when the second refractor is in proximal contact with the first refractor and so that the collimated beam enters the second refractor; and wherein the second refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

26. The apparatus of Claim 25 further comprising an actuator responsive to a control signal operable to control the spacing between the first and second refractors.

27. The apparatus of Claim 25 wherein the first refractor is a prism.

28. The apparatus of Claim 26 wherein the actuator adjusts the spacing between the first and second refractor by a varied and controlled amount so that a first portion of the collimated beam is reflected by the first refractor's reflective surface and a second portion of the collimated beam is reflected by the second refractor's reflective surface.

29. The apparatus of Claim 25 further comprising:
a third refractor having a first reflective surface for reflecting the collimated beam by total internal reflection after reflection by one of the first reflective surface and the second refractor's reflective surface;
a fourth refractor having a contact surface and a reflective surface;
wherein the fourth refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the third refractor's first reflective surface when the fourth refractor is in proximal contact with the third refractor and so that the collimated beam enters the fourth refractor; and wherein the fourth refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

30. An apparatus for switching a plurality of input optical signals to a plurality of output optical locations, the apparatus comprising:
a lens for collimating each input optical signal into a collimated beam; and a reflector for reflecting each collimated beam and having a plurality of positions for changing the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

31. The apparatus of Claim 30 further comprising a decollimating lens for decollimating and focusing each collimated beam.

32. The apparatus of Claim 31 further comprising a return loop coupled to the collimator and decollimator operable to route an optical signal from the decollimator to the collimator.

33. The apparatus of Claim 30 wherein the collimator is further operable to decollimate and focus each collimated beam.

34. The apparatus of Claim 30 wherein the collimator comprises a GRIN lens.

35. The apparatus of Claim 31 wherein the decollimating lens comprises a GRIN lens.

36. The apparatus of Claim 30 wherein the reflector comprises a mirror.

37. The apparatus of Claim 30 further comprising a return loop having a first end and a second end, both the first end and second end are coupled to the collimating lens, the return loop is operable to route an optical signal from the first end to the second end so that the plurality of input optical signals are switched to the plurality of output optical locations.

38. The apparatus of Claim 31 further comprising a return loop having a first end and a second end, both the first end and second end are coupled to the decollimating lens, the return loop is operable to route an optical signal from the first end to the second end so that the plurality of input optical signals are switched to the plurality of output optical locations.

39. The apparatus of Claim 30 further comprising an actuator responsive to a control signal for moving the reflector between the plurality of positions.

40. The apparatus of Claim 39 wherein the actuator comprises a piezo-electrical device.

41. An apparatus for switching a plurality of input optical signals to a plurality of output optical locations, the apparatus comprising:
a lens for collimating each input optical signal into a collimated beam; and a reflector for reflecting each collimated beam. and having a plurality of positions for changing the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations, wherein the reflector further comprises;
a first refractor having a first reflective surface for reflecting each collimated beam by total internal reflection, a second refractor having a contact surface and a reflective surface, wherein the second refractor's contact surface is operable to frustrate the total internal reflection of each collimated beam by the first refractor's first reflective surface when the second refractor is in proximal contact with the first refractor and so that each collimated beam enters the second refractor, and wherein the second refractor's reflective surface is operable to reflect each collimated beam and to change the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

42. The apparatus of Claim 41 further comprising an actuator responsive to a control signal operable to control the spacing between the first and second refractor.

43. The apparatus of Claim 41 further comprising a decollimating lens for decollimating and focusing the collimated beam.

44. The apparatus of Claim 43 further comprising a return loop coupled to the collimating lens and decollimating lens operable to route an optical signal from the decollimating lens to the collimating lens.

45. The apparatus of Claim 41 further comprising a return loop having a first end and a second end, both the first end and second end are coupled to the collimating lens, the return loop is operable to route an optical signal from the first end to the second end so that the plurality of input optical signals are switched to the plurality of output optical locations.

46. The apparatus of Claim 43 further comprising a return loop having a first end and a second end, both the first end and second end are coupled to the decollimating lens, the return loop is operable to route an optical signal from the first end to the second end so that the plurality of input optical signals are switched to the plurality of output optical locations.

47. The apparatus of Claim 41 wherein the first refractor is a prism.

48. The apparatus of Claim 41 further comprising:
a third refractor having a contact surface and a reflective surface;
wherein the first refractor further comprises a second reflective surface for reflecting each collimated beam by total internal reflection after reflection by one of the first refractor's first reflective surface and the second refractor's reflective surface;
wherein the third refractor's contact surface is operable to frustrate the total internal reflection of each collimated beam by the first refractor's second reflective surface when the third refractor is in proximal contact with the first refractor and so each collimated beam enters the third refractor; and wherein the third refractor's reflective surface is operable to reflect each collimated beam and to change the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

49. The apparatus of Claim 48 further comprising a second actuator responsive to a control signal operable to control the spacing between the first and third refractors.

50. The apparatus of Claim 41 further comprising:
a third refractor having a first reflective surface for reflecting each collimated beam by total internal reflection after reflection by one of the first refractor's first reflective surface and the second refractor's reflective surface;
a fourth refractor having a contact surface and a reflective surface;
wherein the fourth refractor's contact surface is operable to frustrate the total internal reflection of each collimated beam by the third refractor's first reflective surface when the fourth refractor is in proximal contact with the third refractor and so that each collimated beam enters the fourth refractor; and wherein the fourth refractor's reflective surface is operable to reflect each collimated beam and to change the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

51. An apparatus for switching a plurality of input optical signals to a plurality of output optical locations, the apparatus comprising:
a lens for collimating each input optical signal into a collimated beam;
a first reflector for reflecting each collimated beam; and a second reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of each collimated beam by a selected amount in order to direct each collimated beam to a different one of the output optical locations.

52. The apparatus of Claim 51 wherein the collimating lens is further operable to decollimate and focus each collimated beam after reflection by the first and second reflectors.

53. The apparatus of Claim 51 wherein the first and second reflectors comprise mirrors.

54. The apparatus of Claim 51 further comprising an actuator responsive to a control signal for moving the second reflector between the plurality of positions.

55. The apparatus of Claim 51 wherein the actuator comprises a piezo-electrical device.

56. The apparatus of Claim 51 further comprising a return loop having a first end and a second end, both the first end and second end are coupled to the collimating lens, the return loop is operable to route an optical signal from the first end to the second end so that the plurality of input optical signals are switched to the plurality of output optical locations.

57. An apparatus for switching a plurality of input optical signals to a plurality of output optical locations, the apparatus comprising:
a lens for collimating each input optical signal into a collimated beam;
a first reflector for reflecting each collimated beam;
a second reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of each collimated beam by a selected amount in order to direct each collimated beam to a different one of the output optical locations, wherein the first and second reflectors are embodied in a first refractor having a first reflective surface for reflecting each collimated beam by total internal reflection and a second reflective surface for reflecting each collimated beam;
a second refractor having a contact surface and a reflective surface;
wherein the second refractor's contact surface is operable to frustrate the total internal reflection of each collimated beam by the first refractor's reflective surface when the second refractor is in proximal contact with the first refractor and so that each collimated beam enters the second refractor; and wherein the second refractor's reflective surface is operable to reflect each collimated beam and to change the angle of the collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

58. The apparatus of Claim 57 further comprising an actuator responsive to a control signal operable to control the spacing between the first and second refractors.

59. The apparatus of Claim 57 wherein the first refractor is a prism.

60. The apparatus of Claim 57 further comprising:
a third refractor having a first reflective surface for reflecting each collimated beam by total internal reflection after reflection by one of the first refractor's first reflective surface and the second refractor's reflective surface;
a fourth refractor having a contact surface and a reflective surface;
wherein the fourth refractor's contact surface is operable to frustrate the total internal reflection of each collimated beam by the third refractor's first reflective surface when the fourth refractor is in proximal contact with the third refractor and so that each collimated beam enters the fourth refractor; and wherein the fourth refractor's reflective surface is operable to reflect each collimated beam and to change the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

61. An apparatus for variably splitting an input optical signal to a plurality of output optical locations, the apparatus comprising:
a lens for collimating the input optical signal into a collimated beam;
a first refractor having a first reflective surface for reflecting the collimated beam by total internal reflection and for changing the angle of the collimated beam by a selected amount in order to direct the beam to the output optical location;
a second refractor having a contact surface and a reflective surface;
an actuator responsive to a control signal operable to the control spacing between the second refractor and the first refractor so as to partially frustrate the total internal reflection of the collimated beam by the first refractor's reflective surface and so that a portion of the collimated beam enters the second refractor and is not directed to the output optical location; and wherein the lens is further operable to decollimate and focus the collimated beam.

62. The apparatus of Claim 61 wherein the actuator is further operable to variably control the spacing between the first refractor so as to regulate the portion of the collimated beam that enters the second refractor.

63. An apparatus for variably splitting an input optical signal between a plurality of output optical locations, the apparatus comprising:
a first lens for collimating the input optical signal into a collimated beam;
a second lens for decollimating and focusing the collimated beam;
a first refractor having a first reflective surface for reflecting the collimated beam by total internal reflection and for changing the angle of the collimated beam by a selected amount in order to direct the beam to a first output optical location;
a second refractor having a contact surface and a reflective surface;
an actuator responsive to a control signal for controlling the spacing between the second refractor and the first refractor so as to partially frustrate the total internal reflection of the collimated beam by the first refractor's reflective surface and so that a portion of the collimated beam enters the second refractor and a remaining portion is reflected by the first refractor's reflective surface; and wherein the reflective surface of the second refractor is further operable to reflect the portion of the collimated beam and to change the angle of the portion in order to direct the portion of the beam to a second output optical location.

64. The apparatus of Claim 63 wherein the actuator is further operable to variably control the spacing between the first refractor and second refractor so as to regulate the portion of the collimated beam that enters the second refractor.

65. A method for switching an input optical signal to one of a plurality of output optical locations, the method comprising the steps of:
collimating the input optical signal into a collimated beam;
directing the collimated beam to one of the output optical locations; and changing the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the output optical locations.

66. The method of Claim 65 further comprising the step of decollimating and focusing the collimated beam prior to the directing step.

67. The method of Claim 65 wherein the changing the angle step further comprises reflecting the collimated beam with a reflector having a plurality of positions, each position changes the angle of the collimated beam by a selected amount.

68. The method of Claim 65 wherein the changing the angle step further comprises:
first reflecting the collimated beam with a reflector having a plurality of positions, each position changes the angle of the collimated beam by a selected amount; and second reflecting the collimated beam with a fixed reflector after the first reflecting step so as to change the angle of the collimated beam again.

69. The method of Claim 65 wherein the changing the angle step further comprises reflecting the collimated beam with a reflector having a plurality of positions, each position changes the angle of the collimated beam by a selected amount.

70. The method of Claim 65 wherein the changing the angle step further comprises changing the angle of the collimated beam by a first amount by reflecting the collimated beam by total internal reflection with a first refractor having a reflective surface, changing the angle of the collimated beam by a second amount by frustrating the total internal reflection of the collimated beam by controlling the spacing between a second refractor having a reflective surface and the first refractor's reflective surface, and reflecting the collimated beam with the second refractor's reflective surface.

71. The method of Claim 65 further comprising the steps of further changing the angle of the collimated beam by a third amount by reflecting the collimated beam by total internal reflection with a second reflective surface of the first refractor.

72. The method of Claim 65 further comprising the steps of changing the angle of the collimated beam by a fourth amount by frustrating the total internal reflection of the collimated beam by controlling the spacing between a third refractor having a reflective surface and the first refractor's second reflective surface, and reflecting the collimated beam with the third refractor's reflective surface.

73. The method of Claim 70 further comprising the step of changing the angle of the collimated beam by a third amount by reflecting the collimated beam by total internal reflection with a third refractor having a first reflective surface after reflection of the collimated beam by one of the first refractor's reflective surface and the second refractor's reflective surface.

74. A method for switching a plurality of input optical signals to a plurality of output optical locations, the method comprising the steps of:
collimating each of the input optical signals into a collimated beam;
directing each collimated beam to one of the output optical locations; and changing the angle of each collimated beam by a selected amount in order to direct each beam to a different one of the output optical locations.

75. The method of Claim 74 further comprising the step of decollimating and focusing the collimated beam prior to the directing step.

76. The method of Claim 74 wherein the changing the angle step further comprises reflecting each collimated beam with a reflector having a plurality of positions, each position changes the angle of each collimated beam by a selected amount.

77. The method of Claim 74 wherein the changing the angle step further comprises:
first reflecting each collimated beam with a reflector having a plurality of positions, each position changes the angle of each collimated beam by a selected amount; and second reflecting each collimated beam with a fixed reflector after the first reflecting step so as to change the angle of each collimated beam again.

78. The method of Claim 74 wherein the changing the angle step further comprises reflecting each collimated beam with a reflector having a plurality of positions, each position changes the angle of each collimated beam by a selected amount.

79. The method of Claim 74 wherein the changing the angle step further comprises changing the angle of each collimated beam by a first amount by reflecting each collimated beam by total internal reflection with a first refractor having a reflective surface, changing the angle of each collimated beam by a second amount by frustrating the total internal reflection of each collimated beam by controlling the spacing between a second refractor having a reflective surface and the first refractor's reflective surface, and reflecting each collimated beam with the second refractor's reflective surface.

80. The method of Claim 74 further comprising the steps of further changing the angle of the collimated beam by a third amount by reflecting the collimated beam by total internal reflection with a second reflective surface of the first refractor.

81. The method of Claim 74 further comprising the steps of changing the angle of the collimated beam by a fourth amount by frustrating the total internal reflection of the collimated beam by controlling the spacing between a third refractor having a reflective surface and the first refractor's second reflective surface, and reflecting the collimated beam with the third refractor's reflective surface.

82. The method of Claim 79 further comprising the step of changing the angle of each collimated beam by a third amount by reflecting the collimated beam by total internal reflection with a third refractor having a first reflective surface after reflection of the collimated beam by one of the first refractor's reflective surface and the second refractor's reflective surface.

83. A system for switching a plurality of input optical signals to a plurality of output optical signals, the system comprising;
a switch array comprising a plurality of switches, each switch comprising:
a plurality of optical inputs and outputs;
a lens for collimating an optical signal from an input into a collimated beam; and a reflector for reflecting the collimated beam and having a plurality of positions for changing the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the switch's outputs, each position corresponding to one of the switch's outputs; and a controller for controlling the switching of optical signals within each switch in the switch array so that each input optical signal is directed to a desired output optical signal.

84. The system of Claim 83 wherein the switch array is organized into first and second switch stages.

85. The system of Claim 83 wherein each switch's reflector comprises:
a first refractor having a first reflective surface for reflecting the collimated beam by total internal reflection;
a second refractor having a contact surface and a reflective surface;
wherein the second refractor's contact surface is operable to frustrate the total internal reflection of the collimated beam by the first refractor's first reflective surface when the second refractor is brought into proximal contact with the first refractor and so that the collimated beam enters the second refractor; and wherein the second refractor's reflective surface is operable to reflect the collimated beam and to change the angle of the collimated beam by a selected amount in order to direct the beam to a different one of the switch's outputs.