WO2003046638A1

WO2003046638A1 - Diffractive optical switch

Info

Publication number: WO2003046638A1
Application number: PCT/FR2001/003771
Authority: WO
Inventors: Pierre Pfeiffer; Patrice Twardowski; Philippe Gerard; Christine Mahodaux
Original assignee: Highwave Optical Technologies; Universite Louis Pasteur
Priority date: 2001-11-28
Filing date: 2001-11-28
Publication date: 2003-06-05
Also published as: WO2003046638A8; AU2002216150A1

Abstract

The invention concerns a switch designed to direct selectively an optical signal from an input element towards an output element, characterized in that it comprises a diffractive optical element (100) capable of receiving an optical beam in input and delivering the beam in output along a direction depending of the impact point of the input beam on said diffractive element and means (200) for displacing the diffractive optical element (100) transversely to the input optical beam between two spaced apart positions.

Description

DIFFRACTIVE OPTICAL SWITCH

The present invention relates to the field of optical components.

More specifically, the present invention relates to the field of optical switches.

Even more precisely, the present invention relates to an optical switch with single-mode optical fibers making it possible to switch one of N input channels to one of M output channels, N and M each being an integer at least equal to 1, N and M being able to be equal, and preferably at least one of N or M being greater than 1.

Those skilled in the art know that nowadays optical switches are key components usable in many applications, in particular in optical information routing systems, addition and extraction multiplexers, monitoring instrumentation. optical networks, the decongestion of optical networks, the establishment of temporary redundant links in optical networks and other applications of this nature in networks. It is generally recognized that ideally an optical switch should make it possible to direct the light beam from an input channel to an output channel with:

- a minimum of insertion losses, (typically 0.5 to 1.5 dB for N and M <to 2), - a minimum of return on the input channel (return loss), (typically -50 dB) ,

- sufficient isolation between channels (typically 30 to 60 dB),

- a minimum of losses due to the polarization of the light (typically 0.1 dB), - a minimum of temporal dispersion due to the polarization of the light (typically <0.1 ps), and

- cover the largest wavelength range. Different families of optical switches exploiting different mechanisms have already been proposed. However, none of the known switches is entirely satisfactory.

Among the known optical switches, there may be mentioned in particular:

- prism switches, operating by mechanical displacement of a prism. These components are however limited to N and M = 2 because the beam can only be deflected in two directions: in a straight line when the prism is not in the optical path or in a deflected direction, when the prism is inserted in the optical direction;

- liquid crystal switches. These are sensitive to polarization and require a correction related to polarization;

- micro-technology switches often called MEMS corresponding to the initials of the Anglo-Saxon expression Micro Electrical and Mechanical Systems. We can distinguish four types of switches in this family: 1) switches proceeding by buckling of a micro mirror by heating or by electrostatic force (these components are limited to N and M = 2), 2) switches proceeding by displacement by translation or tilting of a micro mirror by electrostatic force (these components are limited to N and M = 2), 3) the switches proceeding by rotation of a micro mirror by electrostatic force (these switches have significant insertion losses) and 4) the switches proceeding by displacement of a waveguide (these switches are limited to N = 1 and have significant losses when M is greater than 2).

- thermo-optical type switches. These switches require high energy consumption and have limited insulation; - acousto-optical type switches. These have significant insertion losses;

- mechanical switches. These switches proceed by tilting the fiber. They are limited to N and M = 2; - polarimetric switches. These proceed by rotation of the polarization. They have low insulation;

- holographic type switches. These proceed by deflection of a beam by a photorefractive crystal. They usually require two crystals in order to eliminate the zero order.

So today, there is no universal solution for optical switches.

The present invention aims to provide a new optical switch meeting the specifications defined above.

In addition, the present invention aims to provide an optical switch of low cost, allowing easy industrialization, in particular mass production, good stability over time, a guaranteed number of switches, a good lifetime.

The aforementioned aims are achieved within the framework of the present invention by means of an optical switch comprising a diffractive optical element capable of receiving an optical beam at the input and delivering the beam at the output in a direction which depends on the point of impact of the beam of input on this diffractive optical element and a means able to move the diffractive optical element relative to the input optical beam between at least two distant positions.

According to another advantageous characteristic of the present invention, the drive means is formed of a micro-actuator capable of moving the diffractive optical element over an amplitude between a few microns and a few tens of microns.

According to another advantageous characteristic of the present invention, the microswitch comprises an optical input coupling element designed to adapt the size and the optical opening of the input beam to the diffractive optical element.

According to another advantageous characteristic of the present invention, the switch further comprises an optical output coupling element designed to adapt the size and the optical opening of the beams from the diffractive optical element to at least one optical output element.

Other characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of nonlimiting examples and in which:

- Figures 1 and 2 schematically represent an optical switch according to the present invention 1x2, in two different positions of the diffractive optical element, - Figure 3 shows a side view of an optical switch according to the present invention further illustrating detail the structure of the drive means of the diffractive optical element,

FIG. 4 represents a plan view of a particular embodiment of such a drive means for the diffractive optical element, - FIG. 5 shows a sectional view of this drive means,

FIG. 6 represents a schematic view of a switch according to the present invention comprising two diffractive optical elements,

FIG. 7 represents a schematic view of a switch according to the present invention of the lxN type,

FIGS. 8 and 9 schematically represent two alternative embodiments of switches according to the present invention of the 1x2 type comprising respectively, at the output of a diffractive optical element, a focusing element for FIG. 8 and two focusing elements associated respectively with an output fiber for FIG. 9, and

- Figure 10 schematically shows a switch according to the present invention of IMxM type.

We will first describe the general structure of an optical switch according to the present invention of type 1 to N, for example 1 to 2, with reference to FIGS. 1 and 2.

As indicated above, the switch according to the present invention essentially comprises an optical element diffractive 100 (or "EOD") capable of receiving an optical beam at the input and delivering the beam at the output in a direction which depends on the point of impact of the input beam on this diffractive optical element and a means 200 designed to move the diffractive optical element 100 transversely to the input optical beam between at least two distant positions, as illustrated respectively in FIGS. 1 and 2.

In FIGS. 1 and 2, the drive means 200 is symbolized in the form of an arrow. Particular embodiments of such a drive means 200 will be described in more detail below.

More specifically still, in the context of the present invention, the input optical beam is preferably conveyed by an optical fiber 300 and the optical beams available at the output of the switch are preferably recovered by output optical fibers 400, 410.

Advantageously, these are single-mode fibers. Furthermore, in the context of the present invention, the optical switch is advantageously equipped, upstream of the diffractive optical element 100, that is to say between the input thereof and the output of the optical fiber 300, a focusing element 350. This has the function of orienting the optical beam coming from the fiber 300 on the diffractive optical element 100 (the focal point is not necessarily on the EOD. Similarly , there is preferably provided downstream of the diffractive optical element 100, that is to say between the output of the latter and the input of the output optical fibers 400, 410, a focusing element 450. That it has the function of focusing the beam from the diffractive optical element 100 on the input of one of the optical fibers 400, 410. In the context of the present invention, the focusing elements 350, 450 are formed of preferably a lens section with an index gradient. As explained previously, the function of the diffractive optical element 100 is to deflect and collimate the incident beam. The translation of the diffractive optical element 100 modifies the angle of deflection of the beam. At the output of the diffractive optical element 100, the beam is injected into the output lens 450 which focuses this beam at an image point on one of the output fibers 400, 410. The position of the image point is a function of the angle of incidence on the lens 450 as well as of the position relative to the optical axis. The output fibers 400, 410 must therefore be placed at the various predefined focal points.

The translation of the diffractive optical element 100 transversely to the input optical beam can be obtained by a micro system 200 comprising an electrostatic actuator.

In the position of the diffractive optical element illustrated in FIG. 1, the output optical beam is directed towards the fiber 410. In the second position of the diffractive optical element 100 illustrated in FIG. 2, the output optical beam is directed to the output fiber

400.

A variant of switch 1 to 2 has been illustrated in FIGS. 1 and 2. However, such a switch can easily be generalized to a switch 1 to N, with N> 2 by providing a drive means 200 capable of moving the 'diffractive optical element 100 successively and on command in a number N of distinct positions and accordingly arranging a number N of output optical fibers, respectively at each predefined focal point.

Note that the solution proposed in the context of the present invention offers many advantages.

The translational movement of the diffractive optical element 100 makes it possible to effect a continuous deflection of the beam. The diffractive optical element 100 also makes it possible to correct the phase deformation of the signal inherent in the deflection. The present invention makes it possible to have more than two output image points. In addition, because the deflection of the beam is continuous with the displacement of the diffractive optical element, the invention allows, with the same principle, to produce a variable attenuator with one output or two outputs having a different coupling rate. The drive means 200 only requires very small displacements, typically less than a hundred micrometers. The present invention, thanks to such a displacement of very limited amplitude, makes possible a manufacturing in micro technology, of the integrated and collective type, guaranteeing good reproducibility in production. In other words, depending on the technology chosen, the actuator 200 produced on the basis of micro technology can include the diffractive optical element 100. This arrangement allows a particularly appreciable collective and totally integrated production.

Preferably in the context of the present invention, the diffractive optical element 100 and the drive means 200 are produced using optical micro technologies (etching) on silicon.

The drive means 200 can be the subject of numerous embodiments. Preferably, it is chosen from the group comprising an electrostatic control means, a piezoelectric transducer, an electromagnet or a stepping motor.

Of course, sufficient free space must be left between the diffractive optical element 100 and on one side the input lens 350, on the other the output lens 450, to allow movement of the diffractive optical element 100 The basic function of the diffractive optical element 100 is that of a concave lens close to a Fresnel lens. The diffractive optical element 100 can thus be adapted to correct the optical aberrations of the input lens 350. Indeed, if the diffractive optical element 100 has a function close to a concave lens, the aberrations of the lens input 350, which is equivalent to a convex lens, can be corrected by the aberrations of the diffractive optical element 100 comparable to a concave lens. Preferably, the output lens 450 is formed of a section of index gradient fiber with a length equal to 0.25 pitch, the term pitch denoting the length of a gradient index lens such that the light can go through a complete cycle within it. Thus, the term pitch can be assimilated to the expression "not optical".

The input fiber 300 has its output positioned on the optical axis of the input lens 350.

The position of the diffractive optical element 100 will preferably be chosen so that the distance between the input lens 350 and the diffractive optical element 100 is equal to the focal length of the input lens 350 minus the focal length of the 'diffractive optical element 100 which minimizes the displacement of the diffractive optical element.

The actuator 200 associated with the diffractive optical element 100 can be fixed either on an auxiliary support, or on the input lens 350, or on the output lens 450.

By taking a focal length close to that of the input lens 350 for the diffractive optical element 100, it is possible to maintain a maximum beam diameter and, by this means, to minimize losses by diffraction. The diffractive optical element 100 is then fixed on the input lens 350.

This solution can in particular easily evolve towards an IxN coupler with N> 2 depending on the displacement of the diffractive optical element.

The calculation of such a lens is done for example as follows.

Knowing the input excitation (typically a spherical wave), we can impose the output response (typically a plane wave). The diffractive optical element 100 fulfilling the function of a concave Fresnel lens with an imposed focal length, the optical transfer function is then optimized using a dedicated computer, by optimizing spherical, chromatic aberrations, astigmatisms and coma. We thus obtain a file representing the matrix of the diffractive optical element and serving as basis for making an engraving mask. This method makes it possible to represent a diffractive optical element in a unique way and makes it possible to reproduce it industrially, by conventional methods in microelectronics. The file used to make the mask can also be optimized according to the burning process.

The displacement of the diffractive optical element 100 can be approximated by Ys = d. (<? 7 #). Tgθ with d the diameter of the optical beam at the exit of the diffractive optical element 100, # the aperture of the diffractive optical element and θ the deflection of the beam induced by the displacement Ys of the diffractive optical element 100.

The table below gives the amplitude of deflection of the beam in degrees as a function of the displacement of the diffractive optical element (EOD) 100, respectively for a beam diameter d = 200 μm and for a beam diameter d = 300 μm and a opening 5 5 of the EOD.

It is understood according to the above formula that the necessary displacement of the diffractive optical element 100 depends on the diameter of the beam and on the number of apertures of the diffractive optical element. Minimal displacement is obtained by reducing the diameter of the incident beam or by reducing the opening of the input lens 350.

For a beam diameter d of around 200 μm, which appears to be an optimal beam size, an opening of the diffractive optical element 100 of 5 5, a displacement of 17.5 μm makes it possible to obtain an angular deflection of 1 °. We previously mentioned an opening of 575. Typically the opening may vary between 5 1, 5 and 5 5 according to the invention. A good compromise seems to be around an aperture number equal to 4 of the lens, and a beam diameter of the order of 300 μm. The amplitude of the separation Δyi of the image points at the output of the lens 450 determines the isolation between channels or outputs (crosstalk) of the system.

The inventors have determined that a center distance of 30 μm between the cores of the output fibers 400, 410, etc. is desirable to guarantee an insulation of less than -50dB. Nevertheless, a solution with a separation between axes of the order of 40 or 50 μm is acceptable, depending on the technology chosen and in particular the outside diameter of the fibers.

A separation of the fibers at the outlet of 30 μm typically corresponds to an angular displacement of 1.3 °. The inventors carried out simulations by calculation on the following assumptions:

- EOD 100 diffraction efficiency: 100%

- size of EOD 100: 500μm

- focal: 2512 microns - Fresnel losses on the EOD 100 neglected

- simulated losses:

. losses of the first GRIN lens (350). attenuation of the optical function of the EOD (100). attenuation of the second GRIN lens (450). spherical and distortion aberrations due to EOD (100)

. EOD diffraction losses (100). The calculations show that the degradation of the attenuation is only 0.12dB for an axial alignment defect of the lμm fiber on the X axis transverse both to the optical input axis and to the direction of movement of the diffractive optical element and on the Y axis which coincides with the direction of movement of the diffractive optical element. Longitudinally, a focusing defect of up to 10 μm on the Z axis only results in an attenuation of 0.04dB (see table 4). Table 2 below gives the optimal exit angle and the coupling losses as a function of a non-optimal position of the diffractive optical element 100.

Table 3 below shows the coupling losses as a function of an offset along the Z axis (for an EOD efficiency of 100%).

Table 4 below shows the tolerance with respect to a cumulative positioning offset (for 100% EOD efficiency).

We observe a maximum degradation of 0.2dB with a position error of 0.6μm on the axes and an inclination of 0.5 ° on each axis.

The converging lenses 350 and 450 can be the subject of different variant embodiments.

They can be made in the form of a gradient index lens (GRIN) having an optical pitch close to 0.35, or a convex piano gradient gradient lens (such a lens has less astigmatism than the previous lens ) or in the form of a gradient index lens having an optical pitch of 0.25 with a half-ball lens.

The output beam of the lens typically has a diameter of between 300 and 500 μm.

Table 5 gives the diameter of the beam at the output of a lens with a gradient index of 0.25 steps.

The table above gives the values of the diameter of the beam corresponding to 99% of the energy of the beam at the output of a lens with an index gradient having a pitch of 0.25. The effective diameter at the output of the diffractive optical element 100 is determined by the distance between the diffractive optical element and the input lens 350 on the one hand, and the focal length of the diffractive optical element 100 on the other hand. The diameter at the output of the diffractive optical element can be approximated by the relation: dE0D ⁼ _s f / (f + L _S ép), d _s representing the diameter of the beam at the output of the input lens 350, f representing the focal length of the diffractive optical element 100 and L _sep representing the distance between the diffractive optical element 100 and the input lens 350.

The invention is however not limited to the type of lenses previously defined.

It extends to any functionally equivalent lens, for example in the form of fibers lensed at the end, or even in the form of a fixed diffractive optical element.

The drive means 200 can also be the subject of numerous variant embodiments.

Preferably, the drive means 200 is based on a technology which allows the integration of the actuator 200 and the diffractive optical element 100. This arrangement makes it possible to simplify the manufacturing procedure and to combine the two functions (displacement and support of the diffractive optical element 100 on a single component).

There is shown diagrammatically in FIG. 3 a switch in accordance with the present invention comprising an actuator 200 and a diffractive optical element 100 integrated integral with the input lens 350.

According to an interesting embodiment of the present invention, the actuator 200 is formed of an electrostatic actuator comprising at least one interdigitated comb of electrodes making it possible to move a plate 110 supporting the diffractive optical element 100. Thus, Figure 4 an alternative embodiment in which there are provided two sets of combs 220, 125 interdigitated respectively on either side of the plate 110. The direction of elongation of strands of the interdigitated combs is parallel to the desired direction of movement for the plate 110 and the diffractive optical element 100.

In a manner known per se, when an electrical voltage is applied to the interdigital comb, the resulting electrostatic force generated between the electrodes moves the plate 110 supporting the diffractive optical element 110.

The plate 110 is held by a set of springs and a slide system guaranteeing translation with a minimum of errors.

More specifically, according to the particular embodiment illustrated in Figure 4, there is provided a first pair of springs 130, 132 disposed between a support frame 129 and two opposite faces of the plate 110, to allow movement in the Y direction commanded by the interdigitated combs 220, 125 with return to the rest position of the plate 110 during the interruption of the control supply voltage and a second pair of springs 134, 136 fixed between the frame 129 and the same opposite faces of the plate 110 to ensure positioning in the X direction. Note in FIG. 4 the presence on the plate 110 of a hole

140. This can be cylindrical, elliptical, rectangular or equivalent. As a variant, the plate 110 may include a set of such holes 140 of circular or rectangular elliptical shape or the like arranged in the axis of translation of the plate. This set of holes can form, with an additional light source and a detector of the photodiode type or a set of photodiodes, a sensor making it possible to produce a servo-control in position of the diffractive optical element 100.

For example, there is illustrated in FIG. 3, two auxiliary emission and reception fibers 142, 144 used to bring the light to the sensor and to receive the beam coming from the latter.

Alternatively, the position sensor of the diffractive optical element 100 can be formed by any equivalent means, for example a capacitive type sensor or the like. In the context of the present invention, the diffractive optical element 100 is preferably directly etched in the silicon plate and receives an anti-reflective layer on either side. There is shown in Figure 5, a sectional view of the actuator 200 according to a particular embodiment of the present invention.

We distinguish in Figure 5 the diffractive optical element 100, a silicon support 128 and one or more interstitial layers 127 in which is engraved the actuator 200 itself.

Of course the present invention is not limited to the particular embodiments which have just been described but extends to any variant in accordance with its spirit. The foregoing description corresponds to variant switches using a diffractive optical element 100 which operates in transmission.

However, the present invention can also be applied to switches incorporating a diffractive optical element working at reflection.

The present invention can also be applied to the production of a variable optical attenuator. In this case, using the basic architecture previously described, the diffractive optical element is designed not to have minimal and uniform losses, but to present a variable and controlled attenuation according to the point of impact of the beam on the surface of the diffractive optical element 100.

Switches comprising a single diffractive optical element 100, previously described, generally operate over a wavelength range limited to approximately 50 nm. A simulation shows that on 30nm of the L band there is no significant loss. In general, we can estimate that on 50nm the losses are minor. This range can however be extended to several hundred nm by using a second diffractive optical element 102 interposed between the first diffractive optical element 100 and the output lens element 450, as illustrated in FIG. 6.

The principle of optical operation is the same as that described above. The lenses 350, 450 are advantageously gradient index lenses with an optical pitch (pitch) of 0.25.

The first diffractive optical element 100 plays the role of a convex piano lens and focuses the beam. The second diffractive optical element 102 transforms the spherical wave into a plane wave and deflects the beam as a function of its displacement. In this case, the first diffractive optical element 100 can be fixed, only the second diffractive optical element 102 being controlled to move by a drive means 200. In this configuration the operating range can be extended from 1300nm to 1650nm, the limitations of the switch not being linked to the diffractive optical element but to the gradient index lenses.

Any spherical and chromatic aberrations of one of the diffractive optical elements 100, 102 can be corrected by the second diffractive optical element in the manner of a pair of optical lenses.

It will be noted that the insertion of a second diffractive optical element does not induce a reduction in the positioning tolerances. The first diffractive optical element 100 which is fixed can be made of silica or other synthetic materials and directly mounted on the input lens 350. The optical function of the diffractive optical element 100 is the optical function of a planar convex lens, while the optical function of the second diffractive optical element 102 is that of a concave lens.

As indicated above, the present invention is not limited to the production of a 1x2 switch but extends to the production of IxN switches and more generally NxM.

Variants have been described previously comprising a single output lens 450 associated with several output fibers 400, 410.

However, according to another variant, it is possible in the context of the present invention to use several associated output lenses 450 respectively each to a single output fiber or to a limited group of such output fibers.

FIG. 7 thus shows a switch according to the present invention comprising an input fiber 300, an input lens 350, a diffractive optical element 100 associated with a displacement actuator 200 and four output lenses 450, 451 , 452, 453 respectively associated with output fibers 400, 410, 420, 430.

Such a variant, although requiring several lenses, calls for a simpler production technology at the output module compared to the solution consisting of a single lens. It also ensures better insulation between channels. In this case, the output lenses 450, 453 only couple the light received from the diffractive optical element, in a single fiber.

The output lenses 450 to 453 are typically sections of fibers with an index gradient of a length equal to a quarter of an optical step. Generally, this arrangement requires placing the output lens 450 to 453 at a greater distance than the variants previously described. However, this variant does not require a greater displacement of the diffractive optical element. There have thus been illustrated in FIG. 8, two variants of switches according to the present invention of the 1x2 type. In the context of FIG. 8, a single output lens 450 ensures the coupling alternately in two output fibers 400, 410. On the contrary according to the variant of FIG. 9, there are two output lenses 450, 451 which couple the light respectively in the output fibers 400, 410. It will be appreciated on comparative examination that the distance d2 separating the input and output lenses in the case of FIG. 9 is greater than the same distance dl in the case of the figure 8.

The distance d2 is determined by the relation: d ₂ = h / tg (α / 2) in which α represents the angle of deflection of the beam by the diffractive optical element and h represents the diameter of the lens with index gradient 450 output. Different configurations can be retained within the framework of the present invention for the production of switches of the NxM type with N and M> to 1.

Preferably, as illustrated in FIG. 10, we use: - N input optical fibers 300, 302, 304, 306 designed to route N input beams,

- N input lenses 350, 352, 354, 356 associated respectively with the output of an input fiber 300, 302, 304, 306,

- N diffractive optical elements each coupled to a respective actuator 200 and arranged respectively with regard to the output of an input lens 350, 352, 354, 356,

- M second diffractive optical elements 102 each associated respectively with a specific actuator,

- M output lenses 450, 451, 452, 453 respectively disposed facing the output of one of the M second diffractive optical elements

102, and

- M output fibers 400, 410, 420, 430 respectively disposed at the output of the output lenses 450, 451, 452, 453.

In this case, each of the first diffractive optical elements 100 is adapted to deflect the beam it receives from the associated input fiber 300, 302, 304 or 306 selectively towards any one of the second diffractive optical elements 102. And each of these second diffractive optical elements 102 is suitable for injecting into the associated output fiber 400, 410, 420 or 430 the beam which it receives, whatever the angle of incidence of the latter.

Preferably in this configuration, the two series of diffractive optical elements are movable, each of the diffractive optical elements being individually displaceable within the same assembly. In other words preferably, the diffractive optical element 100 associated with the lens 350 can be moved independently of the diffractive optical element 100 associated with the adjacent input lens 352. And the same is true for the diffractive optical elements 102 associated with the output lenses 450 to 453. By taking for example α = 2 °, and an output lens diameter 450 h = 1mm, the separation of the output lenses 450 is of the order of 57mm. This separation increases to 103mm if h = 1.8mm.

The tests carried out by the inventors have shown that the present invention allows the production of a component combining miniature dimensions with reduced insertion losses of around 0.7dB considering a diffraction efficiency of 90% of the element diffractive optics 100.

Of course the present invention is not limited to the particular embodiments which have just been described but extends to any variant in accordance with its spirit.

We have previously mentioned, a diffractive optical element moved in translation. The invention can also be applied to variants in which the diffractive optical element is rotated.

The diffractive optical element 100 can be in one diffraction dimension or two diffraction dimensions.

In the embodiments described above, each diffractive optical element 100 or 102, at a given time, supports only one optical signal. As a variant, it is possible to envisage making the diffractive optical element in matrix form capable of taking charge and simultaneously routing several independent optical signals.

Embodiments have been described above in which the diffractive optical element 100 is moved transversely to the axis of the input optical beam. However, as a variant, the diffractive optical element 100 could be displaced longitudinally, that is to say parallel to this optical axis, or even in a more complex movement combining a transverse component and a component parallel to the optical beam.

Claims

1. Switch designed to selectively orient an optical signal from an input element to an output element, characterized in that it comprises a diffractive optical element (100) capable of receiving an optical beam at the input and delivering the output beam in a direction which depends on the point of impact of the input beam on this diffractive optical element and means (200) able to move the diffractive optical element (100) relative to the optical input beam between at least two distant positions.

2. Switch according to claim 1, characterized in that it comprises N element (s) input and M element (s) output with N and M whole number at least equal to 1, as well as means adapted for selectively orienting an optical signal coming from an input element towards an output element, the orientation means comprising at least one diffractive optics element (100) and a member (200) associated with the diffractive optics element ( 100) to ensure on command a controlled movement of the latter suitable for orienting the optical signal.

3. Switch according to one of claims 1 or 2, characterized in that it comprises N input element (s) and M output element (s) with N and M whole number of which at least one is greater than 1, as well as means adapted to selectively orient an optical signal coming from an input element towards an output element, the orientation means comprising at least one diffractive optics element (100) and a member (200 ) associated with the diffractive optics element (100) to ensure, on command, a controlled movement of the latter suitable for orienting the optical signal.

4. Switch according to one of claims 1 to 3, characterized in that it comprises N input element (s) and M output element (s) with N and M whole number each greater than 1, as well as means adapted to selectively orient an optical signal coming from an input element towards an output element, the means orientation comprising at least one diffractive optics element (100) and a member (200) associated with the diffractive optics element (100) to ensure on command a controlled movement of the latter adapted to orient the optical signal.

5. Switch according to one of claims 1 to 4, characterized in that N is different from M.

6. Switch according to one of claims 1 to 4, characterized in that N is equal to M.

7. Switch according to one of claims 1 to 6, characterized in that the displacement means (200) is formed by a micro actuator capable of moving the diffractive optical element over an amplitude between a few microns and a few hundred microns.

8. Switch according to one of claims 1 to 7, characterized in that it further comprises an optical input coupling element (350) for adjusting the size and the optical opening of the input beams to the diffractive optical element (100).

9. Switch according to one of claims 1 to 8, characterized in that it comprises an optical input element (350) for orienting the input beam on the diffractive optical element (100).

10. Switch according to one of claims 1 to 9, characterized in that it further comprises an optical output coupling element (450) for adjusting the size and the optical opening of the beams of the element diffractive optics (100) to an output optical element (400, 410).

11. Switch according to one of claims 1 to 10, characterized in that an optical output element (450) is used to focus the output beams from the diffractive optical element (100) to a chosen output.

12. Switch according to one of claims 1 to 11, characterized in that the diffractive optical element (100) operates by transmission of the optical signals.

13. Switch according to one of claims 1 to 11, characterized in that the diffractive optical element (100) operates by reflection of the optical signals.

14. Switch according to one of claims 1 to 13, characterized in that the diffractive optical element (100) is at a diffraction dimension.

15. Switch according to one of claims 1 to 13, characterized in that the diffractive optical element (100) has two diffraction dimensions.

16. Switch according to one of claims 1 to 15, characterized in that at least one of the inputs or one of the outputs is a single mode optical fiber (300, 400, 410).

17. Switch according to one of claims 1 to 16, characterized in that the diffractive optical element (100) has a spatial attenuation function.

18. Switch according to one of claims 1 to 17, characterized in that the diffractive optical element (100) is produced by etching in a silicon wafer.

19. Switch according to one of claims 1 to 18, characterized in that the diffractive optical element (100) and the drive means (200) are integrated by construction.

20. Switch according to one of claims 1 to 19, characterized in that the opening of the diffractive optical element

(100) is between 571.5 and 575.

21. Switch according to one of claims 1 to 20, characterized in that it further comprises a sensor sensitive to the position of the diffractive optical element (100) capable of controlling the drive means (200) ).

22. Switch according to claim 21, characterized in that the position sensor is an optical sensor.

23. Switch according to one of claims 21 or 22, characterized in that an element (110) supporting the diffractive optical element (100) has at least one opening allowing passage an optical beam for actively controlling the position of the diffractive optical element (100).

24. Switch according to one of claims 1 to 23, characterized in that at least one of the input and / or output optical coupling elements (350, 450) consists of a gradient index lens .

25. Switch according to claim 24, characterized in that the index gradient lens (350, 450) is a converging lens chosen from the group comprising: an index gradient lens having an optical pitch close to 0, 35, a convex piano index gradient lens, or an index gradient lens having an optical pitch of 0.25 with a half-ball lens.

26. Switch according to one of claims 1 to 23, characterized in that at least one of the optical input and / or output coupling elements (350, 450) consists of a microlens fiber.

27. Switch according to one of claims 1 to 23, characterized in that at least one of the input and / or output optical coupling elements is formed of a fixed diffractive optical element.

28. Switch according to one of claims 1 to 27, characterized in that it comprises an optical input or output coupling element (350, 450) common to several input elements (300) or output (400, 410).

29. Switch according to one of claims 1 to 27, characterized in that it comprises an optical input coupling element (350) or output (450) associated respectively with each input element (300) or outlet (400, 410).

30. Switch according to one of claims 1 to 29, characterized in that the drive means is formed of an electrostatic actuator.

31. Switch according to one of claims 1 to 29, characterized in that the drive means (200) is chosen in the group comprising piezoelectric motors and stepper motors.

32. Switch according to one of claims 1 to 31, characterized in that it comprises two diffractive optical elements (100, 102) associated.

33. Switch according to claim 32, characterized in that a first diffractive optical element (100) acts as a convex piano lens focusing the input beam and the second diffractive optical element (102) transforms a spherical wave in plane wave and provides a beam deflection function as a function of its displacement.

34. Switch according to one of claims 32 or 33, characterized in that a first diffractive optical element (100) is fixed while the second diffractive optical element (102) is mobile.

35. Switch according to one of claims 1 to 34, characterized in that it comprises N diffractive optical input elements (100) and M diffractive optical output elements (102), each of the N diffractive optical elements input (100) being adapted to deflect an input beam to any of the M diffractive optical elements (102) of output and each of the M diffractive optical elements of output being adapted to deflect the beam it receives from the any of the N diffractive optical input elements (100) to the same respective output optical element (400, 410, 420, 430).

36. Switch according to one of claims 1 to 35, characterized in that the diffractive optical element (100) is produced in a matrix form suitable for handling and routing several independent optical signals simultaneously.