Multi-channel cavity for optical device for spatially manipulating optical radiation

Abstract

The invention relates to a multi-channel cavity (1) comprising a first optical element (3) and a second optical element (3 '), each having a main face carrying a reflective surface (3b, 3b'), at least one of the reflective surfaces (3b, 3b ') being microstructured. The main faces (3a, 3a ') are placed facing each other such that the reflective surfaces (3b, 3b') are arranged according to a defined geometry of the multi-channel cavity (1). The multi-channel cavity (1) comprises two spacers (2, 2 ') for assembling the first optical element (3) and the second optical element (3'), the spacers (2, 2 ') being securely fastened to the main faces of the first optical element and the second optical element so as to maintain a defined geometry between the two reflective surfaces (3b, 3b').

Description

Technical Field

[0001] The present invention relates to an optical device for manipulating optical radiation. More particularly, the present invention relates to an optical device comprising a multi-channel cavity configured to modify the lateral phase distribution of optical radiation. Background Art

[0002] Document WO2019129954A1 discloses an optical device represented by the acronym MPLC (multi-plane light conversion), which makes it possible to perform any single spatial transformation of optical radiation. This device was originally proposed in the document "Programmable unitary spatial mode manipulation" by Morizur et al., J.Opt.Soc.Am.A / Vol. 27, No. 11 / November 2010, and documents US9250454, WO2019129949 and US2017010463 further propose specific embodiments thereof.

[0003] In the implementation scheme proposed by document WO2019129954A1, and referring to the present application Figure 1a and Figure 1b , the optical device comprises a multi-channel cavity 1, which is composed of a planar support 7 with a receiving surface 7a, an alignment component 4 and an assembly of two reflective optical elements 3, 3' placed facing each other. The first optical element 3 has a microstructured main surface 3a, which faces the interior of the cavity 1. This microstructure is configured to modify the phase of the incident optical radiation, which is reflected multiple times during propagation in the cavity 1 along the general advancement direction P in the cavity. More specifically, the main face 3a of the first optical element 3 includes a plurality of microstructured areas 6, each of which is arranged on the main face 3a to accurately receive the incident optical radiation and apply a primary phase change to it. The alignment component 4 ensures good parallelism between the two reflective optical elements 3, 3', thereby allowing the second optical element 3' to be positioned and oriented.

[0004] Reference may be made to the various prior art documents cited to fully understand how the repeated application of these primary transformations allows for a selected transformation of incident optical radiation and how the optical element 3 can be designed to achieve such a transformation. Reference is also made to these documents for examples of methods for digitally designing microstructures arranged on the main face 3a of the optical element 3. Digital models of these microstructures may be used to manufacture the first optical element 3, for example by photolithography, machining, molding and / or engraving of the optical component.

[0005] In this assembly, it is important to maintain very good parallelism of the order of a few microradians between the two reflective optical elements 3, 3' in order to accurately perform the spatial transformation of the incident optical radiation. This is all the more true the longer the cavity and / or the greater the number of reflections.

[0006] Regardless of the method used to manufacture the optical element carrying the microstructured reflective surface, it may be desirable that the element be composed of a variety of materials. Thus, the optical element may be formed of a solid component (e.g. glass) on which a layer (e.g. a layer formed of a reflective metal) has been formed. The metal layer carries the microstructures, and its exposed surface forms the main surface 3a of the first optical element 3 facing the interior of the cavity 1. By providing the first optical element in the form of a solid component with a functional layer carrying the microstructures, the functions performed by the element can be dissociated. Thus, the properties of the functional layer can be selected for its microstructuring and light reflection properties. The properties of the solid component can be selected to ensure the rigidity of the assembly and, for example, to dissipate the heat generated in the microstructured area 6 by the reflection of the optical radiation.

[0007] Whatever the composition of the first reflective optical element, it may deform with temperature. Since this element is firmly fastened to the support, this deformation may tend to bend it and to cause the reflective surface to deviate angularly from its nominal position at ambient temperature. This is even more true if the first optical element consists of materials with different expansion coefficients. The same observations apply to the second optical element. This deformation affects the parallelism of the two reflective optical elements defining the cavity and therefore the quality of the optical transformation performed on the incident optical radiation. This transformation is particularly sensitive to angular deviations of the reflective surfaces, much more so than to fixed deviations of the relative placement of the optical elements, which do not affect this parallelism.

[0008] The parallelism of the two reflective optical elements of the prior art MPLC optical device may also be affected for other reasons. This is particularly the case when the optical elements 3, 3', the planar support 2 and the alignment member 4 are not made of the same material. Likewise, temperature variations relative to the temperature at which these elements are assembled may lead to variations in the precise positioning of the components relative to each other. The application of mechanical forces (such as vibrations or shocks or direct pressure) on one of these components may also cause this positioning to vary.

[0009] Purpose of the Invention

[0010] The present invention aims to remedy all or some of the above-mentioned drawbacks. More specifically, the object of the present invention is to propose a multichannel cavity for an MPLC device which is more robust to mechanical stresses than the multichannel cavities known in the prior art. In particular, the multichannel cavity according to the present invention can accurately perform a spatial transformation of the incident optical radiation over a wide temperature range. The present invention is particularly applicable to providing a multichannel cavity formed by optical components consisting of materials having expansion coefficients that are not completely the same or including optical components formed by materials having different expansion coefficients. Summary of the invention

[0011] To achieve this objective, the object of the present invention is to propose a multi-channel cavity, which comprises a first optical element and a second optical element, each having a main face that carries a reflective surface, at least one of the reflective surfaces being microstructured. The main faces are placed facing each other so that the reflective surfaces are arranged according to a defined geometry.

[0012] According to the invention, the multi-channel cavity comprises two spacers for assembling the first optical element and the second optical element, which spacers are firmly fastened to the main faces of the first optical element and the second optical element to maintain a defined geometry between the two reflecting surfaces.

[0013] Other advantageous non-limiting features according to the invention (alone or in any technically feasible combination):

[0014] the microstructured reflective surface has a plurality of microstructured areas defining a general direction of advance of the radiation in the cavity, along which the two assembly spacers extend between the first optical element and the second optical element;

[0015] - the microstructured area is arranged on the reflective surface between two assembly spacers;

[0016] - two assembly spacers are arranged symmetrically on both sides of the reflecting surface;

[0017] - The assembled spacer consists of individual wedge-shaped pieces;

[0018] - two assembled spacers form two arms of a wedge having a U-shape;

[0019] - two assembled spacers form two arms of a wedge having an O-shape;

[0020] - two assembly spacers are monolithically integrated into the first optical element or the second optical element on the side of the main faces of the first optical element or the second optical element, the main faces of the first optical element then being assembled directly to the main faces of the second optical element;

[0021] - one dimension of the two assembled spacers is adjustable;

[0022] the optical element carrying the microstructured reflective surface is formed by a solid part provided with a functional layer forming the reflective surface, the solid part and the functional layer having different coefficients of thermal expansion;

[0023] - the two reflecting surfaces are planar and positioned parallel to each other;

[0024] The first optical element and the second optical element have different coefficients of thermal expansion.

[0025] According to another aspect, the present invention provides a multi-channel cavity, which includes a first optical element and a second optical element, wherein the first optical element and the second optical element respectively have a main surface that carries a reflective surface, the reflective surface of the first optical element is microstructured, and the main surfaces are arranged facing each other so that the reflective surfaces are arranged according to a defined geometric shape.

[0026] According to the present invention, the multi-channel chamber comprises:

[0027] a wedge comprising two assembled parts, the wedge being securely fastened to the main face of the first optical element;

[0028] - A support having a receiving surface to which the wedge and the second optical element are securely fastened.

[0029] According to an advantageous feature, the wedge may be U-shaped or O-shaped.

[0030] According to yet another aspect, the present invention provides an MPLC optical device, comprising: a multi-channel cavity (1) according to one of the embodiments disclosed above; and an input stage and / or an output stage assembled to the multi-channel cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features and advantages of the present invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings, in which:

[0032] [ Figure 1a ]

[0033] [ Figure 1b ]

[0034] Figure 1a and Figure 1b Depicting a multi-channel cavity of a prior art MPLC device;

[0035] [ Figure 2a ]

[0036] [ Figure 2b ]

[0037] Figure 2a and Figure 2b depicts an assembled view and an exploded view of a multi-channel chamber according to the present invention, respectively;

[0038] [ Figure 2c ]

[0039] [ Figure 2c ] is a front view of the principal surfaces of the first optical element and the second optical element;

[0040] [ Figure 3a ]

[0041] [ Figure 3b ]

[0042] [ Figure 3c ]

[0043] [ Figure 4 ]

[0044] [ Figure 5 ]

[0045] Figure 3a , Figure 3b , Figure 3c , Figure 4 , Figure 5 Other embodiments of multi-channel chambers according to the present invention are depicted. DETAILED DESCRIPTION

[0046] In very general terms, the present specification relates to an MPLC optical device for manipulating incident optical radiation to form transformed optical radiation. Advantageously, the shape of the incident optical radiation and the shape of the transformed optical radiation are different from each other. The manipulation of the incident optical radiation comprises a controlled modification of the transverse phase distribution of the radiation during a plurality of primary transformations which in combination contribute to performing a defined optical function. This may involve spatial multiplexing or demultiplexing of the incident radiation or any other modal transformation in the spatial domain, such as a controlled change in the shape of the beam constituting the incident optical radiation. For example, it may involve 4 or more primary transformations, such as 8, 10, 12, 14 or even 20 or more elementary transformations.

[0047] The MPLC optical device comprises a multi-channel cavity 1 for transforming incident optical radiation into transformed optical radiation. The optical device may optionally comprise further elements, such as an input stage and / or an output stage, to guide the injection of incident optical radiation and the extraction of transformed optical radiation from the cavity 1, respectively, when the radiation is not simply injected into and / or extracted from the device 1 by simple free space propagation.

[0048] The multi-channel cavity 1 according to the invention and with reference to the attached drawings consists of an arrangement of two optical elements 3, 3', each having a main face 3a, 3a', each of which carries a reflective surface 3b, 3b'. The main faces 3a, 3a' of the two optical elements 3, 3' are placed facing each other so that the reflective surfaces define a specific geometry of the multi-channel cavity 1.

[0049] In the depicted embodiment, the two reflecting surfaces 3b, 3b' are planar and positioned parallel to each other. In this general case, the defined geometry corresponds to a fixed scalar spacing value between the two reflecting surfaces 3b, 3b'.

[0050] However, this configuration of plane and parallel surfaces is not mandatory and more generally, the defined geometry may correspond to a defined spacing distribution separating the reflecting surfaces 3b, 3b' of the two optical elements 3, 3'.

[0051] However, in both cases, whether the defined geometry of the cavity is defined as a scalar or a distribution, it is important that the defined geometry of the cavity does not change over time, particularly under the influence of temperature or external forces, so that the MPLC optical device remains perfectly functional. In other words, it is important that the geometry of the cavity does not deviate or deviate too much from the defined geometry over time.

[0052] The reflective surface 3b, 3b' of at least one of the optical elements 3, 3' is microstructured. For simplicity of presentation, the microstructured reflective surface and the optical element carrying the surface will be referred to as "3b" and "3", respectively, in the remainder of the present disclosure. However, in general, the reflective surface 3b of the first optical element 3 and / or the reflective surface 3b' of the second optical element 3' may be microstructured. If this is not the case, and only one of the optical elements 3 has a microstructured reflective surface 3b, the other optical element 3' has a simple reflective surface 3b', such as a mirror.

[0053] Such a microstructure is configured to modify the spatial phase of incident optical radiation which is reflected multiple times while propagating through the cavity 1 in the general radiation advancement direction P in the cavity. To this end, the microstructured reflective surface can be composed of a plurality of different microstructured areas 6 extending along the advancement direction P. Each microstructured area 6 is precisely arranged on the main face 3b of the optical element to receive incident optical radiation, reflect it and impart a primary phase change to it.

[0054] However, the microstructured areas 6 do not need to be different from one another, and any other microstructure configuration may be suitable as long as it allows to impart a certain transformation of the incident radiation during multiple reflections.

[0055] "Microstructured surface" is understood to mean, for example, that the face or surface may have "pixels" ranging in size from a few micrometers or less to hundreds of micrometers or more. Each pixel has a height of at most a few micrometers or at most a few hundred micrometers relative to the average plane defining the face or surface in question. Thus, a microstructured surface may have a resolution (in its average plane) and a height (in the "peaks and valleys") that may extend from a fraction of the central wavelength of the radiation whose spatial phase is to be modified to hundreds of times that wavelength, or even thousands of times that wavelength.

[0056] The optical elements 3, 3' may have any suitable shape. As already mentioned, these optical elements are chosen so that their reflective surfaces 3b, 3b' are completely flat (except for the microstructure), but this is not essential. In general, the microstructure of the reflective surface 3b (or surfaces) is determined during its digital design according to the shape and relative positioning of the reflective surfaces 3b, 3b' and therefore according to the geometry of the cavity. It is therefore important that this geometry remains stable to allow a precise transformation of the incident optical radiation, in particular when the cavity 1 is subjected to forces tending to deform it, such as those generated during significant temperature excursions.

[0057] It should be noted that there may be a difference between the ideal cavity geometry used to design the microstructure and the measured spacing between the reflective surfaces 3b, 3b', which may be due to manufacturing tolerances of the optical components forming the cavity and assembly tolerances of these components. Such deviations, when stable and moderate over time, do not affect the correct operation of the device, or can be compensated by adjusting the position and angle of the incident optical radiation relative to the cavity.

[0058] The defined geometry therefore corresponds substantially to the spacing distribution between the two reflecting surfaces 3b, 3b' when this distribution is measured at room temperature and without any mechanical stress on the cavity.

[0059] The first optical element 3, the second optical element 3' and all other parts forming the cavity can be selected from any suitable material. The material can be quartz, glass, fused silica, metal or silicon, or even plastic material. Within the scope of the present invention, the parts forming the cavity do not have to be made of materials with the same thermal expansion coefficient.

[0060] The optical elements 3, 3' or some of them may also be formed of a plurality of materials having different thermal expansion coefficients. This is particularly true for the optical element 3 carrying the microstructured reflective surface 3b. Thus, as [ Figure 2a ], the optical element can be formed by a solid part 4 having a functional layer 5, the functional layer forming the microstructured reflective surface 3b, the solid part 4 and the functional layer 5 having different thermal expansion coefficients. In the introduction to the present application, we explained the advantages of this arrangement.

[0061] Thus, the solid part 4 may consist of quartz, glass, fused silica, metal or silicon or a plastic material. For example, the functional layer 5 may consist of a metal (gold, silver, nickel), a dielectric or even an insulating resin (e.g. under the trade name The functional layer 5 may be composed of a resin (e.g., a pre-distributed resin) or may include metal, dielectric or even insulating resin. The functional layer 5 may be formed on the solid part by any suitable technique (assembly, deposition, electroplating, etc.).

[0062] First method

[0063] In order to allow a stable assembly of the first optical element 3 and the second optical element 3', the multi-channel cavity 1 according to the first method also includes two spacers 2, 2' that allow the first optical element 3 and the second optical element 3' to be directly assembled together. The two so-called "assembly" spacers are firmly fastened to the main face 3a of the first optical element 3 and the main face 3a' of the second optical element 3'. Each spacer 2, 2' is firmly fastened to the main face of the first optical element 3 and the main face of the second optical element 3.

[0064] “Securely fastened” is understood to mean holding each assembly spacer 2 , 2 ′ to the two optical elements 3 , 3 ′ without any degrees of freedom.

[0065] They are precisely dimensioned to maintain a defined geometry between the reflecting surfaces 3b, 3b' carried by the main faces 3a, 3a' of the two optical elements 3, 3', even when significant forces are applied to the cavity 1. In other words, significant forces applied to the cavity 1 may deform some of the components constituting the cavity, but these deformations do not preferentially affect the reflecting surfaces 3b, 3b', so that the defined geometry can be maintained. Thus, despite the deflections that may be caused by mechanical forces, such as heat sources, the two reflecting surfaces 3b, 3b' present stable average angles that have a significant impact on the transformations achieved by the cavity. In order to promote this stabilization, the two spacers 2, 2' may be positioned symmetrically on either side of the reflecting surfaces 3b, 3b'.

[0066] Advantageously, as can be seen in the figures, the two assembly spacers 2, 2' extend between the first optical element 3 and the second optical element 3' along the general direction of advance P of the radiation in the cavity. When the multi-channel cavity 1 is formed, the microstructured area 6 is arranged on the reflective surface 3b, which is arranged between the two assembly spacers 2, 2'.

[0067] In this configuration, forces applied to the cavity or deformation of one of the cavity components have little or no effect on the spacing of the reflecting surfaces 3b, 3b' and therefore on the internal geometry of the cavity (whose parameters are firmly fixed due to the presence of the two assembly spacers 2, 2').

[0068] When the spacers 2, 2' are assembled on both sides of the reflecting surface along the advancement direction P, the cavity retains two lateral openings for injecting incident optical radiation therein and for collecting the transformed optical radiation.

[0069] The assembly spacer 2, 2' may take the form of at least one additional component, which is referred to as a "wedge" in the remainder of this specification. For example, the wedge or wedges may be assembled to the main face 3a, 3a' of the optical element 3, 3' using an adhesive material (which may be UV or temperature curable), by mechanical clamping, by laser fusion or by molecular bonding.

[0070] exist Figure 2a and Figure 2b In the embodiment shown, the two assembly spacers 2, 2' consist of two separate wedge-shaped pieces.

[0071] exist[ Figure 3a ] In the embodiment shown, the two assembled spacers 2, 2' form two arms of a single U-shaped wedge. In this configuration, one of the lateral openings of the cavity is closed by the base of the U.

[0072] exist Figure 3b and Figure 3c In the embodiment shown, the two spacers form the two arms of a single O-shaped wedge, by which the two lateral openings of the cavity are then closed.

[0073] However, in order to allow optical radiation to propagate through the lateral openings, the wedge material may be selected to be transparent to the incident or transformed optical radiation and thus allow the optical device to function properly.

[0074] More generally, the spacers 2, 2' may be constructed and assembled together with the optical elements 3, 3' to provide lateral or facial openings that allow the propagation of optical radiation into and out of the cavity 1. These openings may be mechanical or optical in nature, by virtue of the transparency of the material forming the spacers. Alternatively, channels may also be provided in one and / or the other of the first optical element 3 and the second optical element 3', which channels allow the propagation of optical radiation into and out of the cavity 1.

[0075] exist[ Figure 3c In the embodiment shown in FIG. 1 , two face openings, marked E and S, are provided to allow incident radiation to be injected into the cavity and to allow transformed radiation to be emitted from the cavity, respectively. These openings are of mechanical nature and are arranged between the second optical component 3' and the wedge. The dimensions of the second optical component 3' in the general direction of advancement P are smaller than those of the wedge, thus freeing channels on both sides of the second optical component 3', thereby forming openings.

[0076] exist[ Figure 3b ] In the embodiment shown in FIG. 1 , the first facial opening E and the Figure 3c ] is similar to that shown in FIG. 3 , and is arranged between the second optical component 3 'and the wedge. The second facial opening S is arranged between the wedge and the first optical component 3. Therefore, the dimensions of the first optical component 3 and the second optical component 3 ' in the overall advancing direction are both smaller than the dimensions of the wedge. Therefore, this frees up two channels of the facial openings E and S that form the cavity.

[0077] Note that the cavity with the facial opening is compatible with all embodiments shown, not just with the [ Figure 3b ]、 Figure 3c The O-ring wedge shown is compatible.

[0078] Instead of being provided in the form of at least one wedge, the two assembly spacers can be monolithically integrated into the first optical element or the second optical element on the main face side of the first optical element or the second optical element. Figure 4 and Figure 5 These spacers then form protruding parts (relative to the reflecting surface) of the optical element that carries them. In this case, the main face 3a of the first optical element is directly assembled to the main face 3a' of the second optical element via the protruding parts forming the spacers, without the cavity 1 comprising any other parts required for its construction.

[0079] Generally speaking, in this first method, apart from the first and second optical elements and optionally wedges, no components are required to form the multi-channel cavity 1. In particular, no supports need to be provided.

[0080] In an embodiment consistent with this first approach, at least one of the spacers can be configured such that its size extending from one reflective surface to the other reflective surface is adjustable. For example, at least one of the spacers can be equipped with a heating element (such as a resistor), or the spacer can be formed of a piezoelectric material equipped with a control electrode. By controlling the voltage applied to the resistor or electrode, the size of the spacer separating the two optical elements can be finely adjusted to bring them closer to a defined geometry.

[0081] The second method.

[0082] In a second method, it is intended to provide a robust multi-channel chamber 1 and Figure 6 and Figure 7Some embodiments of the multi-channel cavity are shown in FIG. 1 , providing a support 7 with a receiving surface to which the second optical element 3 ′ is firmly fastened (i.e. assembled without any degrees of freedom). This assembly can be done directly or via a cube 4 to allow the second optical element 3 ′ to be oriented toward the support 7, as in [ Figure 6 ] as shown.

[0083] A wedge 8 comprising two assembly parts is also firmly held on the main face 3a of the first optical element 3. The wedge can be a U-shaped or O-shaped wedge, as already presented in the specific implementation consistent with the first method. The first optical element 3 has a microstructured reflective surface. The assembly parts of the wedge 8 are preferably assembled on both sides of the microstructured reflective surface 3b of the first optical element 3, and are advantageously assembled symmetrically. These assembly parts can extend along the general advancement direction P. These assembly parts tend to harden the first optical element 3 on its reflective surface 3b side, which prevents this surface from deforming under the application of force.

[0084] The wedge 8 carrying the first optical element 3 is also securely fastened to the receiving surface of the support 7 in an arrangement defining a defined geometry between the two reflecting surfaces.

[0085] As with the first method, the significant forces applied to the cavity 1 according to the second method may deform some of the components constituting the cavity, in particular the first optical element 3. However, these deformations do not occur preferentially at the reflective surfaces, so the defined geometry can be maintained.

[0086] like[ Figure 7 ], the support 7 does not have to be in contact with the entire extent of one side of the wedge 8 and one side of the second optical element 3'. The support may be an element forming a bridge between these two parts, contacting only on a portion of their sides.

[0087] Of course, the invention is not limited to the two methods and embodiments described and alternative embodiments may be added without departing from the scope of the invention as defined by the claims.

[0088] Thus, the optical device may optionally comprise an input stage and / or an output stage assembled to the cavity to direct the injection of incident optical radiation and the extraction of transformed radiation, respectively. These stages may correspond to an optical fiber or a network of optical fibers (the optical fibers may or may not be lensed), or comprise a laser source, an optical element (such as a dichroic element), a lens, a concave mirror, a polarization controller, a MEMS, a flip / tilt control mirror, an SLM matrix, a diffraction grating, an aperture, a surface treated glass plate. In particular, these stages may be attached to at least one of the edges of the optical element or to at least one of the spacers.

Claims

1. A multi-channel cavity (1), comprising a first optical element (3) and a second optical element (3'), the first optical element and the second optical element respectively having a main surface carrying a reflective surface (3b, 3b'), at least one of the reflective surfaces (3b, 3b') being microstructured, the main surfaces (3a, 3'a) being placed facing each other so that the reflective surfaces (3b, 3b') are arranged according to a defined geometric shape of the multi-channel cavity (1), the multi-channel cavity (1) being characterized in that the multi-channel cavity (1) comprises two spacers (2, 2') for assembling the first optical element (3) and the second optical element (3'), each of the spacers (2, 2') being firmly fastened to a main surface of the first optical element (3) and a main surface of the second optical element (3) so as to maintain the defined geometric shape between the two reflective surfaces (3b, 3b').

2. The multi-channel chamber (1) according to claim 1, wherein: The microstructured reflective surface (3b) has a plurality of microstructured areas which define a general advancement direction (P) of the radiation in the cavity, and the two assembled spacers (2, 2') extend between the first optical element (3) and the second optical element (3') along the general advancement direction (P).

3. The multi-channel chamber (1) according to claim 2, wherein: The microstructured area (6) is arranged on the reflective surface (3b) between the two assembly spacers (2, 2').

4. The multi-channel chamber (1) according to one of claims 1 to 3, wherein: The two assembly spacers (2, 2') are symmetrically arranged on both sides of the reflecting surface (3, 3').

5. The multi-channel chamber (1) according to one of claims 1 to 4, wherein: The assembly spacers (2, 2') are composed of separate wedge-shaped pieces.

6. The multi-channel chamber (1) according to one of claims 1 to 4, wherein: The two assembly spacers (2, 2') form the two arms of a U-shaped wedge.

7. The multi-channel chamber (1) according to one of claims 1 to 3, wherein: The two assembled spacers (2, 2') form the two arms of an O-shaped wedge.

8. The multi-channel chamber (1) according to one of claims 1 to 4, wherein: The two assembly spacers (2, 2') are monolithically integrated into the first optical element (3) or the second optical element (3') on the main surface side of the first optical element (3) or the second optical element (3'), and the main surface of the first optical element (3) is then directly assembled to the main surface of the second optical element (3').

9. The multi-channel chamber (1) according to one of claims 1 to 8, wherein: The dimensions of the two assembly spacers (2, 2') are adjustable.

10. The multi-channel chamber (1) according to one of claims 1 to 9, wherein: The optical element (3) carrying the microstructured reflective surface (3b) is formed by a solid component (4) provided with a functional layer (5), the functional layer (5) forming the reflective surface (3b), the solid component (4) and the functional layer (5) having different thermal expansion coefficients.

11. The multi-channel chamber (1) according to one of claims 1 to 10, wherein: The two reflecting surfaces (3b, 3b') are planar and positioned parallel to each other.

12. The multi-channel chamber (1) according to one of claims 1 to 11, wherein: The first optical element (3) and the second optical element (3') have different thermal expansion coefficients.

13. A multi-channel cavity (1), comprising a first optical element (3) and a second optical element (3'), the first optical element and the second optical element each having a main face carrying a respective reflective surface (3b, 3b'), the reflective surface (3b) of the first optical element (3) being microstructured, and the main faces (3a, 3a') being placed facing each other so that the reflective surfaces (3b, 3b') are arranged according to a defined geometric shape, the multi-channel cavity (1) being characterized in that the multi-channel cavity comprises: a wedge (8) comprising two assembly parts, the wedge (8) being firmly fastened to the main face (3a) of the first optical element (3), the two assembly parts being assembled on both sides of the microstructured reflective surface (3b) of the first optical element (3) to harden it; A support (7) having a receiving surface to which said wedge (8) and said second optical element (3') are securely fastened.

14. The multi-channel chamber (1) according to claim 13, wherein: The wedge is U-shaped or O-shaped.

15. An MPLC optical device, comprising: Multi-channel chamber (1) according to one of the preceding claims; and an input stage and / or an output stage assembled to the multi-channel chamber (1).

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