CA1241560A - Optical multiplexer and demultiplexer - Google Patents
Optical multiplexer and demultiplexerInfo
- Publication number
- CA1241560A CA1241560A CA000410788A CA410788A CA1241560A CA 1241560 A CA1241560 A CA 1241560A CA 000410788 A CA000410788 A CA 000410788A CA 410788 A CA410788 A CA 410788A CA 1241560 A CA1241560 A CA 1241560A
- Authority
- CA
- Canada
- Prior art keywords
- optical
- light
- wavelength
- demultiplexer
- linearly polarized
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 53
- 230000010287 polarization Effects 0.000 claims abstract description 33
- 238000006243 chemical reaction Methods 0.000 claims abstract description 4
- 230000005540 biological transmission Effects 0.000 claims description 9
- 239000013307 optical fiber Substances 0.000 claims description 6
- 230000001419 dependent effect Effects 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 239000010453 quartz Substances 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910021532 Calcite Inorganic materials 0.000 claims description 2
- 239000011521 glass Substances 0.000 description 4
- 239000000835 fiber Substances 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 239000000306 component Substances 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
- G02B6/29305—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating as bulk element, i.e. free space arrangement external to a light guide
- G02B6/2931—Diffractive element operating in reflection
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2706—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
- G02B6/2713—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters cascade of polarisation selective or adjusting operations
- G02B6/272—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters cascade of polarisation selective or adjusting operations comprising polarisation means for beam splitting and combining
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
- G02B6/29361—Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
- G02B6/29362—Serial cascade of filters or filtering operations, e.g. for a large number of channels
- G02B6/29365—Serial cascade of filters or filtering operations, e.g. for a large number of channels in a multireflection configuration, i.e. beam following a zigzag path between filters or filtering operations
- G02B6/29367—Zigzag path within a transparent optical block, e.g. filter deposited on an etalon, glass plate, wedge acting as a stable spacer
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/2938—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/29397—Polarisation insensitivity
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
- G02B6/2766—Manipulating the plane of polarisation from one input polarisation to another output polarisation, e.g. polarisation rotators, linear to circular polarisation converters
Abstract
ABSTRACT:
Optical multiplexer and demultiplexer.
Optical multiplexers and demultiplexers utilize interference filters and optical gratings. It is the object of the invention to reduce the losses caused by the use of gratings and filters. This is achieved by the substantially loss-free conversion of unpolarized light into linearly polarized light, so that the efficiency of the filters and gratings is improved. Furthermore, noise is suppressed which is caused by fluctuations in the degree of polarization of unpolarized light because filters and gratings have different characteristics for the different polarization directions.
Optical multiplexer and demultiplexer.
Optical multiplexers and demultiplexers utilize interference filters and optical gratings. It is the object of the invention to reduce the losses caused by the use of gratings and filters. This is achieved by the substantially loss-free conversion of unpolarized light into linearly polarized light, so that the efficiency of the filters and gratings is improved. Furthermore, noise is suppressed which is caused by fluctuations in the degree of polarization of unpolarized light because filters and gratings have different characteristics for the different polarization directions.
Description
~Z4~560 PHN 10.150 l 1.8.1982 Optical multiplexer and demultiplexer.
The invention relates to an optical multiplexer and demultiplexer, comprising at least one first optical fibre for transporting several light signals of different wavelengths, a wavelength-selective member, further optical fibres for transporting at least one light signal in a given waveband~ and a lens system which is arranged between the wavelength-selective member and the fibres, the arrangement being such that low-loss transmission paths which are dependent on the wavelength of the light extend between the first optical fibre and the further optical fibres.
Optical multiplexers and demultiplexers of this kind are known from a publication in "Applied Optics", volume 16, No. 8, August 1977, pages 2180-2194. It has been found that the multiplexers and demultiplexers disclosed in said publication introduce noise into signals transmit-ted in the form of light pulses. The resultant lower signal-to-noise ratio, of course, is undesirable, the more so if said devices are used in telecommunication networks in which the signal-to-noise ratio should remain as high as possible if signals are to be transmitted over long dis-tances via the optical fibres with a minimum number of intermediate amplifiers.
It is an object of the invention to provide optical multiplexers and demultiplexers in which the j signal-to-noise ratio is not affected and in which, more-over, the loss of signal intensity is reduced, so that the signal-to-noise ratio is improved.
To this end, the optical multiplexer and demul-tiplexer in accordance with the invention is characterizedin that between the wavelength-selective member and the ;~ lens system an optical device for the low-loss conversion of unpolarized light into substantially linearly polarized I' ~Z4~560 light is arranged. It has been found that fluctuations in the polarization state of unpolarized light cause noise, because the operation of wavelength-selective mergers (such as an optical grating or filter) is dependent on the degree of polarization of the light. Such fluctuations are eliminated by the linearization of the polarization of the light by the optical device.
It is to be noted that it is known united States Patent 4,153,330) to use double-refractive optical fibres in an optical multiplexer and demultiplexer, said fibres conducting only light having a given polarization direction. The device in accordance with the invention does not require such special fibres.
In accordance with this invention, there is provided an optical multiplexer and demultiplexer, comprising at least one first optical fibre for transporting several light signals of different wavelengths, a wavelength-selective member, further optical fibres for transporting at least one light signal in a given waveband, and a lens system which is arranged between the wavelength-selective member and the fibres, the arrangement being such that low-loss transmission paths, which are dependent on the wavelength of the light extend between the first optical fibre and the further optical fibres, characterized in that between the wavelength-selective member and the lens system~optical device for the low-loss conversion of unpolarized light into substantially linearly polarized light is arranged, said optical device comprising a first optical member for dividing the unpolarized light into two beams of linearly polarized light whose polarization directions are perpendicular to one another, and also comprising a second optical member for rotating the polarization direction of one of ~$
~2g~s60 the beams through an angle of 9O.
Embodiments in accordance with the invention will be described in detail hereinafter with reference to the drawings, in which:
Figure 1 shows a graph with efficiency curves of an optical grating used in optical multiplexers and demultiplexers, Figure 2 shows an embodiment of an optical multiplexer and demultiplexer in accordance with the invention, Figure 3 shows a graph concerning the transmission efficiency of an interference filter, and Figure 4 shows a further embodiment of a multiplexer and demultiplexer in accordance with the invention.
Figure 1 shows a graph with efficiency curves of a reflective grating of an optical multiplexer or demultiplexer.
The graph comprises two curves, one curve being an uninterrupted line (denoted by S) and the other curve being a broken line (de-noted by P). On the vertical axis there is plotted the efficiency n which is determined by the ratio of the energy content of the diffracted light and the energy content of the light incident on the grating. Along the horizontal axis there is plotted the angle e which is the angle at which the light is incident on the grating.
The curve S in the graph relates to linearly - 2a -I` ' -` lZ4~560 PIN 10.150 3 1.8.1982 polarized light, the electrical vector of which is directed transverse to the longitudinal direction of the grooves (S polarization). The curve (P) relates to linearly polarizecl light the electrical vector of which is directed parallel to the grooves of the grating (P polari-zation. It will be clear that for the majority of angles of incidence the efficiency for S polarization is higher than the efficiency of the grating for P polarization.
This is described in detail in a publication in "applied Optics", October 1977, volume 16, No. 10, pages 2711-2721.
igure 2 shows an embodiment of an optical mul-tiplexer and demultiplexer 1 in accordance with tha invention. The device 1 comprises the following known com-ponents in a known arrangement (for example, see Applied Optics, Vol. 18, No. 16, August 1979, pages 2834-2836): an input fibre 3 ~rherethrough light having the wavelengths >~ 2~ ~3 and ~4 is supplied, output fibres 5a, b, c and d wherethrough~ight having the wavelength 2~ ~3 and 4, respectively, is output. The arbitrarily polarized light which is supplied via the input fibre 3 is projected onto the grating 14 via a lens 7 and an optical device 8 which converts the light into two beams of linearly polarized light. The light reflected by the grating 14 is transmitted to the fibres 5a, b, c and d, via the device 8 and lens 7, in dependence on the wavelength.
The optical device 8 comprises two prisms 9 and 11 wherebetween a polarizing filter 10 is arranged. The filter 10 divides the incident light into two beams of linearly polarized light. Light having a polarization direction in the plane of the drawing (denoted by ) is transmitted, whilst light having a polarization direction perpendicular thereto is reflected (denoted by ,). The reflected light is reflected again in the prism 11, passes through a glass filler plate 10 and through a ~/2 plate 12 of crystalline quartz which rotates the polarization direction through an angle of 90, and is subsequently incident on the grating 14. The light transmitted by the ;
~Z4~560 PIIN 10~150 4 1.8.1982 filter 10 passes through a glass filler plate 13 and is directed parallel to the light beam passing through the plate 12. Therefore, all of the input light is incident on the grating 14, as linearly polarized light, which is advantageous, as will be explained hereinafter.
Because the two light beams incident on the grating 14 are linearly polarized in the same direction, fluctuations in the degree of polarization of the light entering via the fibre 3 do not affect the efficiency of -the grating 14. Fluctuations in the degree of polarization of the light incident on a grating introduce noise in the light reflected by the grating, because under the influence of the fluctuations more or less light is reflected with the efficiency associated with the P polarization the S
p0larization.
The grating 14 is used with the highest efficien-cy when the electrical vector of the linearly polarized light is directed at right angles to the grooves (S polari-zation. The use of the device not only prevents the intro-duction of undesirable noise, but also allows more effec-tive use of the grating 14, thus reducing the loss of light.
Figure 3 shows a graph with transmission efficiency curves of an interference filter which can be used in optical multiplexers and demultiplexers. Along the vertical axis there is plotted the transmission efficiency T and the wavelength of the light in nanometres, nm, is plotted along the horizontal axis. For light which is incident perpendicularly to the plane of the interference filter, the transmission curves are identical for light with AS
polarization or P polarization and hence also for unpolari-zed light. In optical multiplexers and demultiplexers, however, the light will usualy be incident on the filter at an angle, so that light with S polarization encounters a different filter, as it were, than light with P polari-zation. The different transmission curves occurring in suchcircumstances for light with S polarization (dotted line) a and light with P polarization (broken line) are shown in 12~S60 PTIN 10.150 5 1.8.1982 the graph. For unpolarized light, the filter has a transmission characteristic 0 (uninterrupted line) which is determined by the arithmetical mean value of the P curve and the S curve. It will be clear that when interference filters are used in multiplexers and demultiplexers, the use of an optical device for convertîng unpolarized light into linearly polarized light reduces noise (in the case of fluctuations in the polarization degree of the unpola-rized light ) and at the same time improves the efficiency.
Figure 4 shows a further embodiment of a multi-plexer and demultiplexer 20 in accordance with the invention, the optical fibres and lens systems having been omitted for the sake of simplicity. An incoming beam 21 of unpolarized light of different wavelengths 2~
,~3 and A 4 is converted, by means to be described, into two beams of nearly polarized light whose polarization direction is perpendicular to the plane of the drawing.
colour shifter 25, which is composed of three prisms 26 27 and 28 wherebetween interference filters 31, 32 and 33 are arranged, splits the two beams of linearly polarized light, depending on wavelength, into four beams 41, 42, 43 and 44 of linearly polarized light having wavelengths
The invention relates to an optical multiplexer and demultiplexer, comprising at least one first optical fibre for transporting several light signals of different wavelengths, a wavelength-selective member, further optical fibres for transporting at least one light signal in a given waveband~ and a lens system which is arranged between the wavelength-selective member and the fibres, the arrangement being such that low-loss transmission paths which are dependent on the wavelength of the light extend between the first optical fibre and the further optical fibres.
Optical multiplexers and demultiplexers of this kind are known from a publication in "Applied Optics", volume 16, No. 8, August 1977, pages 2180-2194. It has been found that the multiplexers and demultiplexers disclosed in said publication introduce noise into signals transmit-ted in the form of light pulses. The resultant lower signal-to-noise ratio, of course, is undesirable, the more so if said devices are used in telecommunication networks in which the signal-to-noise ratio should remain as high as possible if signals are to be transmitted over long dis-tances via the optical fibres with a minimum number of intermediate amplifiers.
It is an object of the invention to provide optical multiplexers and demultiplexers in which the j signal-to-noise ratio is not affected and in which, more-over, the loss of signal intensity is reduced, so that the signal-to-noise ratio is improved.
To this end, the optical multiplexer and demul-tiplexer in accordance with the invention is characterizedin that between the wavelength-selective member and the ;~ lens system an optical device for the low-loss conversion of unpolarized light into substantially linearly polarized I' ~Z4~560 light is arranged. It has been found that fluctuations in the polarization state of unpolarized light cause noise, because the operation of wavelength-selective mergers (such as an optical grating or filter) is dependent on the degree of polarization of the light. Such fluctuations are eliminated by the linearization of the polarization of the light by the optical device.
It is to be noted that it is known united States Patent 4,153,330) to use double-refractive optical fibres in an optical multiplexer and demultiplexer, said fibres conducting only light having a given polarization direction. The device in accordance with the invention does not require such special fibres.
In accordance with this invention, there is provided an optical multiplexer and demultiplexer, comprising at least one first optical fibre for transporting several light signals of different wavelengths, a wavelength-selective member, further optical fibres for transporting at least one light signal in a given waveband, and a lens system which is arranged between the wavelength-selective member and the fibres, the arrangement being such that low-loss transmission paths, which are dependent on the wavelength of the light extend between the first optical fibre and the further optical fibres, characterized in that between the wavelength-selective member and the lens system~optical device for the low-loss conversion of unpolarized light into substantially linearly polarized light is arranged, said optical device comprising a first optical member for dividing the unpolarized light into two beams of linearly polarized light whose polarization directions are perpendicular to one another, and also comprising a second optical member for rotating the polarization direction of one of ~$
~2g~s60 the beams through an angle of 9O.
Embodiments in accordance with the invention will be described in detail hereinafter with reference to the drawings, in which:
Figure 1 shows a graph with efficiency curves of an optical grating used in optical multiplexers and demultiplexers, Figure 2 shows an embodiment of an optical multiplexer and demultiplexer in accordance with the invention, Figure 3 shows a graph concerning the transmission efficiency of an interference filter, and Figure 4 shows a further embodiment of a multiplexer and demultiplexer in accordance with the invention.
Figure 1 shows a graph with efficiency curves of a reflective grating of an optical multiplexer or demultiplexer.
The graph comprises two curves, one curve being an uninterrupted line (denoted by S) and the other curve being a broken line (de-noted by P). On the vertical axis there is plotted the efficiency n which is determined by the ratio of the energy content of the diffracted light and the energy content of the light incident on the grating. Along the horizontal axis there is plotted the angle e which is the angle at which the light is incident on the grating.
The curve S in the graph relates to linearly - 2a -I` ' -` lZ4~560 PIN 10.150 3 1.8.1982 polarized light, the electrical vector of which is directed transverse to the longitudinal direction of the grooves (S polarization). The curve (P) relates to linearly polarizecl light the electrical vector of which is directed parallel to the grooves of the grating (P polari-zation. It will be clear that for the majority of angles of incidence the efficiency for S polarization is higher than the efficiency of the grating for P polarization.
This is described in detail in a publication in "applied Optics", October 1977, volume 16, No. 10, pages 2711-2721.
igure 2 shows an embodiment of an optical mul-tiplexer and demultiplexer 1 in accordance with tha invention. The device 1 comprises the following known com-ponents in a known arrangement (for example, see Applied Optics, Vol. 18, No. 16, August 1979, pages 2834-2836): an input fibre 3 ~rherethrough light having the wavelengths >~ 2~ ~3 and ~4 is supplied, output fibres 5a, b, c and d wherethrough~ight having the wavelength 2~ ~3 and 4, respectively, is output. The arbitrarily polarized light which is supplied via the input fibre 3 is projected onto the grating 14 via a lens 7 and an optical device 8 which converts the light into two beams of linearly polarized light. The light reflected by the grating 14 is transmitted to the fibres 5a, b, c and d, via the device 8 and lens 7, in dependence on the wavelength.
The optical device 8 comprises two prisms 9 and 11 wherebetween a polarizing filter 10 is arranged. The filter 10 divides the incident light into two beams of linearly polarized light. Light having a polarization direction in the plane of the drawing (denoted by ) is transmitted, whilst light having a polarization direction perpendicular thereto is reflected (denoted by ,). The reflected light is reflected again in the prism 11, passes through a glass filler plate 10 and through a ~/2 plate 12 of crystalline quartz which rotates the polarization direction through an angle of 90, and is subsequently incident on the grating 14. The light transmitted by the ;
~Z4~560 PIIN 10~150 4 1.8.1982 filter 10 passes through a glass filler plate 13 and is directed parallel to the light beam passing through the plate 12. Therefore, all of the input light is incident on the grating 14, as linearly polarized light, which is advantageous, as will be explained hereinafter.
Because the two light beams incident on the grating 14 are linearly polarized in the same direction, fluctuations in the degree of polarization of the light entering via the fibre 3 do not affect the efficiency of -the grating 14. Fluctuations in the degree of polarization of the light incident on a grating introduce noise in the light reflected by the grating, because under the influence of the fluctuations more or less light is reflected with the efficiency associated with the P polarization the S
p0larization.
The grating 14 is used with the highest efficien-cy when the electrical vector of the linearly polarized light is directed at right angles to the grooves (S polari-zation. The use of the device not only prevents the intro-duction of undesirable noise, but also allows more effec-tive use of the grating 14, thus reducing the loss of light.
Figure 3 shows a graph with transmission efficiency curves of an interference filter which can be used in optical multiplexers and demultiplexers. Along the vertical axis there is plotted the transmission efficiency T and the wavelength of the light in nanometres, nm, is plotted along the horizontal axis. For light which is incident perpendicularly to the plane of the interference filter, the transmission curves are identical for light with AS
polarization or P polarization and hence also for unpolari-zed light. In optical multiplexers and demultiplexers, however, the light will usualy be incident on the filter at an angle, so that light with S polarization encounters a different filter, as it were, than light with P polari-zation. The different transmission curves occurring in suchcircumstances for light with S polarization (dotted line) a and light with P polarization (broken line) are shown in 12~S60 PTIN 10.150 5 1.8.1982 the graph. For unpolarized light, the filter has a transmission characteristic 0 (uninterrupted line) which is determined by the arithmetical mean value of the P curve and the S curve. It will be clear that when interference filters are used in multiplexers and demultiplexers, the use of an optical device for convertîng unpolarized light into linearly polarized light reduces noise (in the case of fluctuations in the polarization degree of the unpola-rized light ) and at the same time improves the efficiency.
Figure 4 shows a further embodiment of a multi-plexer and demultiplexer 20 in accordance with the invention, the optical fibres and lens systems having been omitted for the sake of simplicity. An incoming beam 21 of unpolarized light of different wavelengths 2~
,~3 and A 4 is converted, by means to be described, into two beams of nearly polarized light whose polarization direction is perpendicular to the plane of the drawing.
colour shifter 25, which is composed of three prisms 26 27 and 28 wherebetween interference filters 31, 32 and 33 are arranged, splits the two beams of linearly polarized light, depending on wavelength, into four beams 41, 42, 43 and 44 of linearly polarized light having wavelengths
2' ~3 and 4, respectively.
The optical device 20 comprises a plate 22 of uniaxial anisotropic material, for example, calcite, sapphire or rutile which splits the unpolarized light into two beams of linearly polarized light whose polarization directions are perpendicular to one another. The beam of light which is not deflected has a polarization direction in the plane of the drawing and passes through a ~/2 plate 23 of crystalline quartz, so that the polarization direction becomes perpendicular to the plane of the drawing, Due to the extraordinary refraction in the plate 22, the light having a polarization direction perpendicu-; 35 lar to the plane of the drawing is deflected to the colour shifter 25 via a glass filler plate 24. The beams emerging via the /2 plate 23 and via the glass plate 24 are parallel to one another.
- :~L24~S60 PI-IN 10.150 6 1.8.1982 In order to obtain correct refraction, the propagation direction of the light must be perpendicular to the plate 22 and the optical axis of the material of the plate 22 must enclose an angle with respect to the S surface thereof. This angle is determined my the arc tan-gent of the quotient of the extraordinary and the ordinary refractive indices.
The optical device 20 comprises a plate 22 of uniaxial anisotropic material, for example, calcite, sapphire or rutile which splits the unpolarized light into two beams of linearly polarized light whose polarization directions are perpendicular to one another. The beam of light which is not deflected has a polarization direction in the plane of the drawing and passes through a ~/2 plate 23 of crystalline quartz, so that the polarization direction becomes perpendicular to the plane of the drawing, Due to the extraordinary refraction in the plate 22, the light having a polarization direction perpendicu-; 35 lar to the plane of the drawing is deflected to the colour shifter 25 via a glass filler plate 24. The beams emerging via the /2 plate 23 and via the glass plate 24 are parallel to one another.
- :~L24~S60 PI-IN 10.150 6 1.8.1982 In order to obtain correct refraction, the propagation direction of the light must be perpendicular to the plate 22 and the optical axis of the material of the plate 22 must enclose an angle with respect to the S surface thereof. This angle is determined my the arc tan-gent of the quotient of the extraordinary and the ordinary refractive indices.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An optical multiplexer and demultiplexer, comprising at least one first optical fibre for transporting several light signals of different wavelengths, a wavelength-selective member, further optical fibres for transporting at least one light signal in a given waveband, and a lens system which is arranged between the wavelength-selective member and the fibres, the arrangement being such that low-loss transmission paths, which are dependent on the wavelength of the light extend between the first optical fibre and the further optical fibres, characterized in that between the wavelength-selective member and the lens system an optical device for the low-loss conversion of unpolarized light into substantially linearly polarized light is arranged, said optical device comprising a first optical member for dividing the unpolarized light into two beams of linearly polarized light whose polarization directions are perpendicular to one another, and also comprising a second optical member for rotating the polarization direction of one of the beams through an angle of 90°.
2. An optical multiplexer and demultiplexer as claimed in Claim 1, characterized in that the first optical member comprises a flat plate of uniaxial, anisotropic material, for example, calcite, the propagation direction being directed perpendicularly thereto whilst the optical axis of said plate encloses an angle with respect to the propagation direction which is determined by the arc tangent of the quotient of the extraordinary and the ordinary refractive indices.
3. An optical multiplexer and demultiplexer as claimed in Claim 2, characterized in that the second optical member is a flat .lambda./2 plate of crystalline quartz.
4. An optical multiplexer and demultiplexer as claimed in claim 1, 2 or 3 characterized in that the wavelength-selective member is an optical grating, the electrical vector of the linearly polarized light being directed to right angles to grooves of the optical grating.
5. An optical multiplexer and demultiplexer as claimed in Claim 1, 2 or 3 characterized in that the wavelength-selective member is an interference filter.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL8104123 | 1981-09-07 | ||
NL8104123A NL8104123A (en) | 1981-09-07 | 1981-09-07 | OPTICAL MULTIPLEX AND DEMULTIPLEX DEVICE. |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1241560A true CA1241560A (en) | 1988-09-06 |
Family
ID=19838023
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000410788A Expired CA1241560A (en) | 1981-09-07 | 1982-09-03 | Optical multiplexer and demultiplexer |
Country Status (8)
Country | Link |
---|---|
US (1) | US4741588A (en) |
EP (1) | EP0074143B1 (en) |
JP (1) | JPS5882220A (en) |
AU (1) | AU550888B2 (en) |
CA (1) | CA1241560A (en) |
DE (1) | DE3267610D1 (en) |
DK (1) | DK394482A (en) |
NL (1) | NL8104123A (en) |
Families Citing this family (69)
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US6496622B1 (en) * | 2001-04-25 | 2002-12-17 | Chromaplex, Inc. | Diffractive structure for high-dispersion WDM applications |
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US7120333B2 (en) * | 2001-10-25 | 2006-10-10 | Lambda Crossing, Ltd. | Polarization insensitive tunable optical filters |
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JP4368286B2 (en) * | 2004-10-08 | 2009-11-18 | 富士通株式会社 | Optical switch device |
US7466502B2 (en) * | 2005-12-07 | 2008-12-16 | Tessera North America, Inc. | Optical wavelength division coupler and associated methods |
CA2616311C (en) * | 2005-07-22 | 2014-09-30 | Tessera North America, Inc. | Optical wavelength division coupler and associated methods |
KR101176187B1 (en) * | 2007-11-21 | 2012-08-22 | 삼성전자주식회사 | Stacked semiconductor device and method for thereof serial path build up |
US9134479B2 (en) * | 2012-09-05 | 2015-09-15 | International Business Machines Corporation | Polarization diverse demultiplexing |
JP2019066629A (en) * | 2017-09-29 | 2019-04-25 | 株式会社フジクラ | Substrate type optical waveguide and introducing method |
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US4385799A (en) * | 1980-06-26 | 1983-05-31 | Sperry Corporation | Dual array fiber liquid crystal optical switches |
JPS57157003A (en) * | 1981-03-20 | 1982-09-28 | Toshiba Corp | Casing for steam turbine |
US4571024A (en) * | 1983-10-25 | 1986-02-18 | The United States Of America As Represented By The Secretary Of The Air Force | Wavelength selective demultiplexer tuner |
US4566761A (en) * | 1984-09-13 | 1986-01-28 | Gte Laboratories Incorporated | Birefringent optical wavelength multiplexer/demultiplexer |
-
1981
- 1981-09-07 NL NL8104123A patent/NL8104123A/en not_active Application Discontinuation
-
1982
- 1982-08-26 US US06/411,927 patent/US4741588A/en not_active Expired - Fee Related
- 1982-08-31 DE DE8282201073T patent/DE3267610D1/en not_active Expired
- 1982-08-31 EP EP82201073A patent/EP0074143B1/en not_active Expired
- 1982-09-03 AU AU87985/82A patent/AU550888B2/en not_active Ceased
- 1982-09-03 CA CA000410788A patent/CA1241560A/en not_active Expired
- 1982-09-03 DK DK394482A patent/DK394482A/en not_active Application Discontinuation
- 1982-09-07 JP JP57154757A patent/JPS5882220A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
EP0074143B1 (en) | 1985-11-21 |
NL8104123A (en) | 1983-04-05 |
DE3267610D1 (en) | 1986-01-02 |
US4741588A (en) | 1988-05-03 |
DK394482A (en) | 1983-03-08 |
AU550888B2 (en) | 1986-04-10 |
JPS5882220A (en) | 1983-05-17 |
EP0074143A1 (en) | 1983-03-16 |
AU8798582A (en) | 1983-03-17 |
JPH0322961B2 (en) | 1991-03-28 |
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