REFLECTOR DEVICE

Description

TECHNICAL FIELD

[0001] The invention relates to a reflector device, and in particular a reflector device that experiences little or no heating during operation. In this respect, the reflector device comprises a partially transparent mirror behind which are arranged means for thermal diffusion and / or absorption. PREVIOUS STATE OF THE ART

[0002] Micromirrors are now widely used in the field of MEMS and in particular in LIDAR (“Light Detection And Ranging systems”) type devices.

[0003] These devices allow, in particular, the scanning of a surface or target with light radiation for detection or imaging purposes.

[0004] In this regard, in these LIDAR-type devices, the micro-mirrors are arranged to oscillate around one or two pivot axis(s), at a predetermined beat frequency, so as to reflect incident radiation in different directions.

[0005] The beat frequency of micro-mirrors can vary from a few Hz to several kHz, and their size can be on the order of a few millimeters (for example a few millimeters in diameter for disc-shaped micro-mirrors), and can notably be between 1 mm and 3 mm.

[0006] According to a well-known example of the prior art, a micro-mirror may include a metallic reflective layer formed on a main face of a substrate, for example a substrate made of silicon, and in particular of monocrystalline silicon.

[0007] The metallic reflective layer may in particular include a layer of gold or aluminum with a thickness between 50 nm and 500 nm.

[0008] However, this configuration is not satisfactory.

[0009] Indeed, the metallic reflective layer has a non-negligible absorption coefficient of light radiation, so that in operation, particularly when the power of the incident radiation is significant, heating of the micro-mirror is observed.

[0010] This effect can exist when the light radiation is in the infrared range and in particular with a wavelength λ = 1550 nm.

[0011] For example, at this wavelength, a micromirror comprising a reflective metallic layer with a reflection coefficient of 96% and an absorption coefficient of 4% can experience a temperature increase sufficient to lead to the thermomechanical destruction of the mirror.

[0012] Similarly, and under equivalent conditions, a micro-mirror comprising a reflective metallic layer with a reflection coefficient of 98% and an absorption coefficient of approximately 2% can undergo a "theoretical" heating to a temperature close to 2000 °C after about one hundred seconds.

[0013] However, such heating damages the micro-mirrors.

[0014] To address this problem, consideration was given to replacing the metallic reflective layer with a Bragg reflector stack as described in document [1] cited at the end of the description, in order to increase the laser damage threshold of these optical components.

[0015] Such a Bragg reflector stack generally comprises a plurality of elementary reflector stacks arranged to reflect radiation of a predetermined wavelength known as the Bragg length. For example, a Bragg stack designed to operate at a Bragg length of 1550 nm might include a 110 nm thick layer of amorphous silicon and a 305 nm thick layer of silicon dioxide.

[0016] The Bragg reflector stack is weakly or non-absorbent, so no heating of the micro-mirror is observed.

[0017] However, this configuration is also not satisfactory.

[0018] Indeed, in order to maximize the reflection coefficient of the Bragg reflector stack, it generally comprises a large number of elementary reflector stacks, which can lead to deformations due to the mechanical stresses imposed by the increasing number of layers. The increased number of elementary stacks also complicates the manufacturing process of such a reflector.

[0019] Considering a reduced number of elementary reflective stacks affects the micromirror's reflection coefficient. In particular, the latter, being partially transparent, transmits some of the light radiation.

[0020] One aim of the present invention is therefore to propose an optical device equipped with a micro-mirror capable of operating at higher incident radiation powers than conventional metallic mirrors, i.e. with a higher laser damage threshold in both the short and long term.

[0021] Another objective of the present invention is also to propose an optical device equipped with a micro-mirror and arranged to limit the deformations of said mirror.

[0022] The document JP2005337715 describes a bandpass filter for Raman spectroscopy. DESCRIPTION OF THE INVENTION

[0023] The objectives of the present invention are, at least in part, achieved by a reflecting device intended to reflect light radiation of wavelength λ greater than 1250 nm, in particular equal to 1550 nm; the device is provided with a support on which are assembled: a partially transparent mirror, and having a partially reflective front face; means for diffusing and / or absorbing light radiation configured to diffuse and / or absorb, directly, light radiation that may be transmitted through a rear face, opposite to the front face.

[0024] The diffusion and / or absorption means are arranged opposite and at a distance from the rear face.

[0025] Depending on the implementation method, the means of dissemination and / or absorption include: a light-diffusing layer, advantageously a metallic layer, or an absorption layer, advantageously the absorption layer being for example a metallic layer, or a layer formed of carbon nanotubes, or a heat sink comprising a bulk material for example carbon, metal and structured or unstructured to dissipate heat, or an anti-reflective layer, advantageously arranged on means configured to dissipate heat.

[0026] According to one embodiment, the diffusion means comprise a series of first sampling blades, essentially flat or curved (allowing said first sampling blades to diverge), referred to as first blades, each of said first sampling blades being provided with a first front face and a first rear face opposite the first front face. These first blades are aligned along an alignment direction, parallel to each other, and oriented so as to partially reflect the light radiation likely to be transmitted by the rear face, towards a first dissipator (heat sink).

[0027] These initial plates can be highly transparent and have very low absorption. For example, they can reflect a few percent (e.g., 8%) of incident radiation and transmit a few tens of percent (e.g., 92%). These plates can be made of glass, for example, B1664 or BK7 type glass. However, the invention is not limited to these two examples.

[0028] According to one implementation method, at least one first heat sink is arranged perpendicularly to the front face of the mirror.

[0029] According to one implementation method, the first sampling slides are also partially transparent so that the first front face of each of them is exposed to the light radiation that can be transmitted through the back face and through the first sampling slide that precedes it in the path of the radiation.

[0030] According to one embodiment, the diffusion means comprise a series of second sampling blades, for example of the same nature as the first sampling blades, essentially flat or curved (allowing said first sampling blades to be divergent), called first blades, each provided with a second front face and a second rear face opposite to the second front face, the second sampling blades being aligned along an alignment direction, parallel to each other, and oriented so as to reflect in part, and in the direction of a second dissipator, the light radiation likely to be transmitted by the rear face.

[0031] According to one implementation method, the first sampling blades and the second sampling blades are arranged alternately along the alignment direction.

[0032] According to the present invention, it is possible to consider other series of sampling slides, for example, of the same type as the first sampling slides. The sampling slides within a series can also be aligned along an alignment direction, parallel to each other, and oriented so as to partially reflect light towards another heat sink. The first heat sink, the second heat sink, and any other heat sinks that may be considered can be arranged around the alignment direction (in other words, the direction of propagation of the light emanating from the rear face of the micromirror). For example, if three heat sinks were to be considered, their normals could be arranged angularly at 120° to each other around the alignment axis. This concept can be generalized to N heat sinks arranged angularly at 360° / N around the alignment axis.

[0033] The device may also include at least one first diverging lens which is interposed between a first front face (of a first sampling slide) and the first dissipator so as to spread the radiation reflected by said first face towards said first dissipator.

[0034] Equivalently, the device may also include at least one second diverging lens which is interposed between a second front face (of a second sampling blade) and the second dissipator so as to spread the radiation reflected by said second face towards said second dissipator.

[0035] According to one implementation method, the first sampling blades are arranged perpendicularly to the second sampling blades.

[0036] According to one embodiment, the mirror comprises, from its front face to its rear face, a partially reflective layer and a mechanical support layer, said layers each having an absorption coefficient at wavelength λ of less than 0.1%, advantageously zero.

[0037] According to one embodiment, the partially reflective layer comprises a Bragg stack, the Bragg stack comprising at least one elementary Bragg stack.

[0038] According to one embodiment, an elementary Bragg stack comprises a stack of two dielectric and / or semiconducting layers, advantageously an elementary Bragg stack comprises a silicon dioxide layer and an amorphous silicon layer.

[0039] According to one implementation mode, the Bragg stacking is limited to one or two elementary Bragg stacks.

[0040] The invention is not limited to the implementation of one or two elementary Bragg stacks, and a larger number of stacks may be considered as long as the curvature problem of the mirror is controlled.

[0041] According to one implementation method, the mechanical support layer comprises a semiconductor material, advantageously silicon, even more advantageously single-crystal silicon.

[0042] According to one implementation method, a layer, called an impedance matching layer, is configured to limit internal reflections of light radiation within the mirror.

[0043] According to one implementation method, the said device is a LIDAR device. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features and advantages will become apparent in the following description of a reflector device according to the invention, given by way of non-limiting examples, with reference to the accompanying drawings in which: there figure 1 is a schematic representation, according to a first embodiment of the present invention; the figure 2 is a schematic representation, according to a second embodiment of the present invention; the figure 3 is a schematic representation, according to a third embodiment of the present invention; the figure 4 is a schematic representation, according to a fourth embodiment of the present invention; the figure 5 is a schematic representation, according to a fifth embodiment of the present invention; the figure 6 is a schematic representation, according to a sixth embodiment of the present invention; the figures 7a to 7gare schematic representations of an example of a mirror manufacturing process. figure 8 is a schematic representation, according to a seventh embodiment of the present invention; the figure 9 is a schematic representation of a variant of the seventh embodiment of the present invention. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0045] The present invention relates to a reflecting device equipped with a mirror (or micro-mirror) intended to reflect light radiation of higher average and instantaneous optical powers than conventional metallic micro-mirrors without undergoing a significant temperature rise and / or likely to degrade its performance, i.e. with higher laser damage thresholds than conventional micro-mirrors.

[0046] The present invention therefore implements a mirror that absorbs little or no light radiation, coupled with means for dissipating heat from the light flux that may be transmitted by this mirror.

[0047] Throughout the description and in the claims, the expression "light diffusion" may be used interchangeably to describe both diffusion and absorption of light radiation, or deflection of said radiation, or thermal dissipation.

[0048] By "difference", we mean the deviation in several directions of a light beam.

[0049] By "absorbing" we mean the transformation of the energy carried by the light radiation into another form of energy in order to dissipate the latter.

[0050] The term "absorption coefficient" refers to the proportion of incident energy, carried by the light radiation, that is absorbed.

[0051] The term "reflection coefficient" refers to the proportion of incident energy, carried by the light radiation, that is reflected.

[0052] The term "transmission coefficient" refers to the proportion of incident energy, carried by the light radiation, that is transmitted.

[0053] By "deflection" we mean means configured to redirect the reflection of transmitted radiation in a direction other than a rear face of the mirror.

[0054] THE figures 1 to 6 illustrate different ways of implementing a reflective device 10 according to the present invention.

[0055] The reflector device 10 may include support means 21, for example two uprights 21a and 21b, intended to hold a mirror 23 partially transparent to light radiation of a predetermined wavelength λ.

[0056] By "partially transparent" it is understood that a fraction of an incident light radiation I on a front face 24 of the mirror is reflected by said face, while another fraction passes partly through the mirror, and emerges in the form of transmitted radiation T, through a rear face 25 opposite to the front face 24.

[0057] The support means 21a and 21b can in particular be arranged to allow the mirror to pivot around one or two pivot axes.

[0058] The device also includes diffusion and / or absorption means 26 configured to diffuse and / or absorb the transmitted radiation. These diffusion and / or absorption means 26 specifically limit the reflection of radiation towards the mirror 23.

[0059] In this regard, the diffusion and / or absorption means 26 can be arranged opposite and at a distance from the rear face 25 of the mirror 23. In particular, the support means 21 extend from the diffusion and / or absorption means 26.

[0060] According to a first method of implementation illustrated in the figure 1 , the means of diffusion and / or absorption 26 are arranged to absorb the transmitted radiation.

[0061] In this regard, the means 26 may include at least one absorbing layer 27 (or stack of absorbing layers), for example an absorbing metallic layer formed on a main face 22 of a support 20, for example a silicon support.

[0062] Alternatively, the absorbing layer can comprise a layer of powder, in particular a layer of graphite powder. With respect to light radiation with a wavelength of 1550 nm, a layer of graphite powder has low, or even no, transmissivity and also exhibits a very low reflection coefficient (on the order of 0.5%).

[0063] Alternatively, means 26 may comprise, on a support substrate (for example, a silicon support substrate), and from one face of this support substrate, a 200 nm thick titanium layer, a 270 nm thick silicon dioxide layer, a 13 nm thick titanium layer, and a 250 nm thick silicon dioxide layer. In this case, transmitted radiation with a wavelength of 1550 nm will be partially absorbed by the titanium layers and very weakly reflected (the reflection coefficient is less than 1%).

[0064] According to a second method of implementation illustrated in the figure 2 , the means of diffusion and / or absorption 26 include a plate which may be metallic.

[0065] In particular, this plate includes a face opposite the rear face 25, the surface of which is textured 28 so as to distribute the transmitted radiation. The surface texturing may include the creation of 3D patterns, for example, according to a range of spatial periods adjusted to scatter the light radiation of wavelength λ. In particular, the spatial periods considered may be slightly longer than the predetermined wavelength λ. Specifically, if the predetermined wavelength is 1550 nm, the spatial period of the texturing may be between 2 µm and 5 µm.

[0066] The diffusion plate may include an aluminum plate (the face opposite the rear face 25 of which is textured).

[0067] Texturing can also be achieved by dispersing a powder of a chosen particle size onto one face of a supporting substrate.

[0068] According to a third implementation method illustrated in the figure 3 The means of diffusion and / or absorption 26 may include a reflective plate, one face of which has a texture 29, in particular faceted protrusions, intended to deflect the transmitted radiation in a direction other than that of the mirror. The faceted protrusions may include pyramids (for example, with 3 or 4 facets).

[0069] According to a fourth implementation method illustrated in the figure 4 , the diffusion and / or absorption means 26 may include a layer of carbon nanotubes 30 formed on a support substrate, in particular a silicon substrate.

[0070] According to a fifth embodiment illustrated in the figure 5, the diffusion and / or absorption means 26 may include a heat sink 31, in particular a finned heat sink made of anodized aluminum.

[0071] The heat sink 31 can, in particular, be coupled to the reflector device 10 via an intermediate support 32.

[0072] The intermediate support 32 may be provided with a recess 33 allowing the transmitted radiation to reach the heat sink 31

[0073] According to a sixth implementation method illustrated in the figure 6 , the means of diffusion and / or absorption 26 includes a heat dissipating device on which an anti-reflective layer is formed.

[0074] The heat sink may in particular incorporate the characteristics of the first or fifth embodiment.

[0075] The anti-reflective coating can notably be Aeroglaze Z-306 ®< .

[0076] According to a seventh embodiment illustrated in the figure 8 , the diffusion means 26 include a series of first sampling slides 34a, 34b, 34c, essentially flat or curved, each provided with a first front face 35a and a first rear face 35b opposite the first front face 35a.

[0077] The first sampling blades 34a, 34b, 34c are aligned along an alignment direction XX' and parallel to each other. They are also oriented to partially reflect, towards a first dissipator 36, the light radiation that may be transmitted from the rear face 25. The first dissipator 36 can, for example, be positioned perpendicular to the front face 24 of the mirror 23. The first sampling blades can be mounted to pivot.

[0078] Furthermore, the first sampling slides 34a, 34b, 34c can also be partially transparent so that the first front face 35a of each of them is exposed to the light radiation that can be transmitted through the rear face 25 and passing through the first sampling slide that precedes it in the path of the radiation.

[0079] The first blades can, for example, reflect the light radiation likely to be emitted by the rear face at a reflection angle either close to 45 degrees or close to 90° to said light radiation, and in the direction of the first heat sink.

[0080] The advantage of the dissipation methods used in this implementation, with initial sampling blades, is their ability to dissipate the energy of the light radiation that may be transmitted through the rear face at different points or regions of the first heat sink. These methods specifically allow for the "spreading" of the flux associated with the light radiation that may be transmitted through the rear face.

[0081] It is also possible to adjust this spread by adjusting the spacing between the first slats. For example, the first slats can be placed closer together as you move away from the back.

[0082] Thus, if the intensity of the light radiation likely to be emitted by the rear face is I₀, the intensity actually received on the first front face of a given first sampling slide is equal to Tn < x I₀, where T is the transmission coefficient of a first sampling slide and n is the number of first sampling slides preceding the given first sampling slide along the path of the light radiation. Consequently, adjusting the spacing between first sampling slides depends on T (T is less than 1, for example, equal to 0.9), on I₀, but also on the heat dissipation properties of at least one heat sink.

[0083] These initial plates can be highly transparent and have very low absorption. For example, they can reflect a few percent (e.g., 8%) of incident radiation and transmit a few tens of percent (e.g., 92%). These plates can be made of glass, for example, B1664 or BK7 type glass. However, the invention is not limited to these two examples.

[0084] The mirror 23 can finally be surmounted by a transparent window 37 arranged on a base 38. The base 38 can have an opening intended to reveal the back face of the mirror 23.

[0085] Thus, during operation, the light radiation that can be transmitted by a rear face 25 passes successively through the first sampling blades 34a, 34b, and 34c. A portion of this radiation is nevertheless reflected by each of the first front faces 35b towards the dissipating screen 36. The implementation of several first sampling blades according to this seventh embodiment thus makes it possible to distribute the energy to be dissipated at different locations on the dissipating screen 36.

[0086] This distribution is also dependent on the spacing between the first sampling slides. In this respect, the spacing between these slides may decrease as one moves away from the back surface.

[0087] The first sampling plates 34a, 34b, and 34c may comprise a glass, for example BK7, or silicon coated with an elemental Bragg stack comprising a layer of silicon dioxide and a layer of amorphous silicon. The first sampling plates 34a, 34b, and 34c may be square, measuring 5 mm by 5 mm. The first heat sink 36 may be square, for example, measuring 5 cm by 5 cm.

[0088] The first heat sink 36 may include a non-reflective absorbing layer, by means of a powder layer, in particular a layer of graphite powder on a silicon support.

[0089] The device may also include at least one first diverging lens which is interposed between a first front face (of a first sampling slide) and the first dissipator so as to spread the radiation reflected by said first face towards said first dissipator.

[0090] Finally, the assembly formed by the first heat sink and the first sampling blades can advantageously be separated from the micromirror and its support. This feature notably improves the efficiency of heat dissipation without the risk of reintroducing heat by conduction into the micromirror and / or its support.

[0091] There figure 9 represents a variant of this seventh embodiment.

[0092] According to this variant, the diffusion means 26 comprise a series of second sampling blades 39a and 39b, essentially flat, each provided with a second front face 40a and a second rear face 40b opposite the second front face. The second sampling blades 39a and 39b are further aligned along the alignment direction XX', parallel to each other, and oriented so as to partially reflect, towards a second dissipator 41, the light radiation that may be transmitted by the rear face (25).

[0093] According to this variant, the first sampling slides 34a, 34b and the second sampling slides 39a, 39b are arranged alternately along the alignment direction. The first sampling slides may, for example, be perpendicular to the second sampling slides.

[0094] Furthermore, the first sampling slides and the second sampling slides may include the same material.

[0095] Equivalently, the first heat sink screen and the second heat sink screen can comprise the same material.

[0096] The device may also include at least one second diverging lens which is interposed between a second front face (of a second sampling blade) and the second dissipator so as to spread the radiation reflected by said second face towards said second dissipator.

[0097] According to the present invention, it is possible to consider other series of sampling slides, for example, of the same type as the first sampling slides. The sampling slides within a series can also be aligned along an alignment direction, parallel to each other, and oriented so as to partially reflect light towards another heat sink. The first heat sink, the second heat sink, and any other heat sinks that may be considered can be arranged around the alignment direction (in other words, the direction of propagation of the light emanating from the rear face of the micromirror). For example, if three heat sinks were to be considered, their normals could be arranged angularly at 120° to each other around the alignment axis. This concept can be generalized to N heat sinks arranged angularly at 360° / N around the alignment axis.

[0098] Regardless of the implementation method considered, the coupling of the diffusion and / or absorption means 26 with the retention means 21a and 21b can be achieved by bonding.

[0099] In particular, the bonding can be performed using an adhesive, or include metal-to-metal bonding or molecular bonding.

[0100] The mirror 23 may include from its front face to its rear face, a partially reflective layer 11 and a mechanical support layer 12, said layers each having a negligible absorption coefficient at wavelength λ, advantageously zero.

[0101] According to a particularly advantageous variant, the partially reflective layer 11 may include a Bragg stack (or Bragg mirror), the Bragg stack comprising at least one elementary Bragg stack.

[0102] By "Bragg stacking" we mean a periodic succession of transparent, or partially transparent, layers with different refractive indices.

[0103] An elementary Bragg stack comprises a stack of two dielectric and / or semiconducting layers.

[0104] In particular, when the radiation is in the infrared range, and more specifically of wavelength equal to 1550 nm at normal incidence, the elementary Bragg stack can include a layer of silicon dioxide with a thickness of 305 nm (whose refractive index at 1550 nm is 1.44) covered with a layer of amorphous silicon with a thickness of 110 nm (whose refractive index at 1550 nm is 3.42).

[0105] In this configuration, a Bragg stack consisting of a single elementary Bragg stack will exhibit, at an angle of incidence of 20°, a reflection coefficient of 82.4% and a transmission coefficient of 17.6% when faced with light radiation of a wavelength of 1550 nm. At an angle of incidence of 45°, the reflection coefficient is 80.9% and the transmission coefficient is 19.1%. Furthermore, this stack will not be absorbent and will exhibit virtually no heating.

[0106] In this configuration, a Bragg stack comprising two elementary Bragg stacks will exhibit, at a radiation angle of 45°, a reflection coefficient of 96.4% and a transmission coefficient of 3.6% against light with a wavelength of 1550 nm. This stack will also exhibit little or no absorption and will generate virtually no heat.

[0107] The aforementioned stacks, as well as any other stack that may be implemented within the framework of the present invention, can be formed on a mechanical support layer made, for example, of a semiconducting or dielectric material.

[0108] The choice of material may, for example, be dictated by the wavelength λ. As an example, the absorption coefficient of a mechanical support layer is negligible, or even zero, for wavelengths greater than 1250 nm. In other words, a mechanical support layer made of single-crystal silicon with a thickness between 20 µm and 100 µm will experience heating that will not be detrimental to the mirror.

[0109] Limiting the number of elementary Bragg stacks reduces the mechanical stresses imposed on the mirror, thus preventing any deformation (e.g., curvature) of said mirror.

[0110] Furthermore, the combination of such a mirror with means of dissipation and / or absorption also makes it possible to limit, or even prevent, the heating of said mirror when high-power incident light radiation, in particular infrared radiation, is used.

[0111] Advantageously, the mechanical support layer can comprise a semiconductor material, advantageously silicon, even more advantageously single-crystal silicon.

[0112] The formation of a layer, called an impedance matching layer, configured to limit internal reflections of light radiation within the mirror can also be considered.

[0113] The impedance matching layer may in particular include silicon nitride when the substrate is silicon.

[0114] Figures 7a to 7h illustrate an example of a manufacturing process for mirror 10.

[0115] The process includes, in particular, step a) ( figure 7a ) which consists of providing a silicon-on-insulator substrate 100 (“SOI”), comprising a layer of monocrystalline silicon covering a layer of silicon dioxide formed on a monocrystalline silicon substrate.

[0116] Alternatively, step a) may include the provision of a bulk substrate (for example a silicon substrate) on one face of which a layer of silicon dioxide and a layer of polycrystalline silicon are formed successively.

[0117] Step a) is followed by step b) which includes the formation of a Bragg 110 stack ( figure 7b ) on the silicon layer of the SOI substrate. The 110 stacking notably includes a Bragg stacking.

[0118] The Bragg stack shown in this figure includes in particular two elementary Bragg stacks each made of a layer of silicon dioxide, 305 nm thick, and amorphous silicon, 110 nm thick.

[0119] Step b) is followed by a formation step c) of, in order, a protective layer 130, a lower electrode 140, a PZT layer 150, and an upper electrode 160 ( figure 7c ).

[0120] A step d) of hard mask formation 170 ("hard mask" according to Anglo-Saxon terminology) is then executed ( figure 7d ). This hard mask 170, which may include silicon dioxide, is intended to allow the release of the mirror by etching from a back face of the SOI substrate.

[0121] Electrode patterns 180a and 180b, as well as contact points 190a, 190b, 190c and 190d, are formed in step e) illustrated in the figure 7e .

[0122] The mirror pattern is defined by the creation of 200 trenches by a front face, which extend into the substrate support SOI ( figure 7f ).

[0123] Finally, as illustrated in the figure 7g , an engraving is performed on the back face of the SOI substrate support to release the mirror.

[0124] The invention is not limited to a mirror made according to the process described above. REFERENCES

[0125] [1] Harald Schenk et al., “Micro Mirrors for high-speed Laser Deflection and Patterning”, Physics Procedia, 56 (2014) 7-18.

Claims

1. Reflector device (10) intended to reflect luminous radiation of wavelength λ, greater than 1250 nm, particularly equal to 1550 nm, the device is provided with a supporting base whereon are assembled: - a partially transparent mirror (23), having a partially reflective front face (24); - luminous radiation scattering and / or absorption means (26), disposed facing and away from the rear face (25), opposite the front face (24), configured to scatter and / or absorb, directly, luminous radiation liable to be transmitted by said rear face (25).

2. Device according to claim 1, wherein the scattering and / or absorption means comprise: - an absorption layer, advantageously the absorption layer comprises a metallic layer or - a layer having a textured exposed surface, particularly metallic, or - a layer formed of carbon nanotubes, or - a heat sink, or - an anti-reflective layer, and advantageously disposed on means configured to dissipate heat.

3. Device according to claim 1, wherein the scattering means (26) comprise a series of first collection strips, essentially flat, each provided with a first front face and a first rear face opposite the first front face, the first collection strips being aligned along an alignment direction, parallel with one another, and oriented so as to partially reflect, toward a first dissipator, the luminous radiation liable to be transmitted by the rear face (25).

4. Device according to claim 3, wherein the first dissipator is disposed perpendicularly to the front face (24) of the mirror (23).

5. Device according to claim 3 or 4, wherein the first collection strips are furthermore partially transparent such that the first front face of each thereof is exposed to the luminous radiation liable to be transmitted by the rear face (25) and traversing the first collection strip preceding same on the path of the radiation.

6. Device according to one of claims 3 to 5, wherein the scattering means (26) comprise a series of second collection strips, essentially flat, each provided with a second front face and a second rear face opposite the second front face, the second collection strips being aligned along the alignment direction, parallel with one another, and oriented so as to partially reflect, toward a second dissipator, the luminous radiation liable to be transmitted by the rear face (25).

7. Device according to claim 6, wherein the first collection strips and the second collection strips are disposed in alternation along the alignment direction.

8. Device according to claim 7, wherein the first collection strips are disposed perpendicularly to the second collection strips.

9. Device according to one of claims 1 to 8, wherein the mirror (23) comprises from the front face (24) thereof to the rear face (25) thereof, a partially reflective layer (11) and a mechanical supporting base layer (12), said layers having, each, an absorption coefficient at the wavelength λ less than 0.1%.

10. Device according to claim 9, wherein the partially reflective layer comprises a Bragg stack, the Bragg stack comprising at least one elementary Bragg stack, advantageously, an elementary Bragg stack comprises a stack of two dielectric and / or semiconductor layers, advantageously an elementary Bragg stack comprises a layer of amorphous silicon and a layer of silicon oxide.

11. Device according to claim 10, wherein the Bragg stack is limited to one or two elementary Bragg stacks.

12. Device according to one of claims 9 to 11, wherein the mechanical supporting base layer comprises a semiconductor material, advantageously silicon, even more advantageously monocrystalline silicon.

13. Device according to one of claims 1 to 12, wherein a so-called impedance matching layer is configured to limit internal reflections of the luminous radiation within the mirror.

14. Device according to one of claims 1 to 13, wherein said device is a LIDAR device.