Wavelength demultiplexing device in particular for out-of-plane demultiplexing

Patent metadata

Field	Value
Publication number	US-2022011516-A1
Application number	US-202117305347-A
Country	US
Kind code	A1
Filing date	Jul 6, 2021
Priority date	Jul 7, 2020
Publication date	Jan 13, 2022
Grant date	—

Abstract

A wavelength demultiplexing device configured so as to spatially distributing the spectral contributions of an incident light beam, when in use, and which includes a linear waveguide and a planar waveguide, formed in a coplanar way and adapted to be optically coupled with one another along a coupling line, by evanescent coupling. Such a device may further include diffraction gratings located in the planar waveguide, to extract light out of the latter.

First claim

1 . A wavelength demultiplexing device configured to spatially distribute the spectral contributions of an incident light beam when in use, wherein:
a linear waveguide, adapted to perform an optical guidance along a guide line and over a use wavelength range; and a planar waveguide, adapted to perform an optical guidance in a guide plane and over said use wavelength range; with the linear waveguide and the planar waveguide formed in a coplanar way, and configured so as to be optically coupled with one another by evanescent coupling along a coupling line, when in use, a distance between the linear waveguide and the planar waveguide varying decreasingly, along the coupling line and in the direction of propagation of light in the linear waveguide, when in use.

2 . The device according to claim 1 , wherein the planar waveguide comprises a core layer an edge of which opposite the coupling line is bent upon itself so as to form an indentation, and wherein the linear waveguide is bent upon itself, and located inside the indentation formed in the planar waveguide.

3 . The device according to claim 1 , further comprising:
an extraction assembly located in the planar waveguide, and consisting of a plurality of diffraction grating each configured to extract light out of the planar waveguide; with each of the diffraction gratings of the extraction assembly configured so as to extract light at a different wavelength called extraction wavelength.

4 . The device according to claim 3 , wherein the diffraction gratings of the extraction assembly are positioned so that, in an orthogonal projection of the diffraction gratings on the coupling line, these are arranged in the descending order of their extraction wavelength, along the coupling line and in the direction of propagation of light in the linear waveguide when in use.

5 . The device according to claim 3 , wherein, in an orthogonal projection of the diffraction gratings on the coupling line, these are arranged in the ascending order of their extraction rate, along the coupling line and in the direction of propagation of light in the linear waveguide when in use.

6 . The device according to claim 3 , wherein, in each of the diffraction gratings of the extraction assembly, the patterns of the diffraction grating are disposed along lines which are orthogonal to a direction of propagation of light in the planar waveguide at said diffraction grating.

7 . The device according to claim 3 , wherein the planar waveguide includes a core layer interposed between two optical cladding layers, and wherein the diffraction gratings extend in one of the optical cladding layers, or in a superficial region of the core layer at an interface between the core layer and one amongst the two optical cladding layers.

8 . The device according to claim 3 , wherein:
the planar waveguide comprises a core layer an edge of which opposite the coupling line is bent upon itself so as to form an indentation,
the linear waveguide is bent upon itself, and located inside the indentation formed in the planar waveguide; and
the device further includes a support substrate, transparent over the use wavelength range, superimposed with the planar waveguide along an axis orthogonal to the plane of the planar waveguide, with the support substrate which is provided with a through opening located opposite a portion of at least one indentation formed in the planar waveguide.

9 . The device according to claim 8 , wherein the through opening is delimited by at least one transverse face, which extends from one face to the opposite face of the support substrate, and wherein said transverse face includes a curved surface or a series of facets inclined obliquely with respect to the plane of the planar waveguide.

10 . The device according to claim 9 , wherein each of the diffraction gratings is configured so as to extract light at its extraction wavelength, according to a respective extraction axis directed obliquely with respect to the plane of the planar waveguide, with the extraction axis directed so that light reaches said transverse face at a normal incidence.

11 . The device according to claim 8 , comprising a pedestal, transparent over the use wavelength range, and located opposite the through opening formed in the support substrate.

12 . An infrared imaging system comprising:
a wavelength demultiplexing device according to claim 8 , configured so as to distribute on a scene to be illuminated light rays originating from an appended light source, when in use; and an imaging module, including an array infrared detector configured so as to receive light rays sent back by the scene to be illuminated; with the array infrared detector located opposite at least one portion of the indentation formed in the planar waveguide, on the side of the planar waveguide opposite to the support substrate.

13 . The system according to claim 12 , further comprising an infrared light source forming the appended light source, and wherein the wavelength demultiplexing device is configured so as to receive at input light rays originating from said infrared light source and distribute these rays on the scene to be illuminated, when in use.

14 . The system according to claim 12 , comprising a spacing element, mounted secured to the imaging module and provided with a bearing surface intended to come into contact with a sample to be analysed and located on one side of the spacing element opposite to the imaging module, and wherein the wavelength demultiplexing device forms all or part of the spacing element.

Assignees

• Commissariat Energie Atomique

Inventors

• Monpeurt Cyrielle
• Boutami Salim

Classifications

• H04N23/20

  for generating image signals from infrared radiation only · CPC title

• G02B6/29386 Primary

  Interleaving or deinterleaving, i.e. separating or mixing subsets of optical signals, e.g. combining even and odd channels into a single optical signal · CPC title

• G02B6/2938 Primary

  for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM · CPC title

• G02B6/12007 Primary

  forming wavelength selective elements, e.g. multiplexer, demultiplexer · CPC title

• G02B6/29332

  Wavelength selective couplers, i.e. based on evanescent coupling between light guides, e.g. fused fibre couplers with transverse coupling between fibres having different propagation constant wavelength dependency · CPC title