Device for distributing a signal for measuring wavelength shifts

Patent metadata

Field	Value
Publication number	US-12098936-B2
Application number	US-202017609133-A
Country	US
Kind code	B2
Filing date	May 6, 2020
Priority date	May 7, 2019
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

A signal-distributing device that includes an arrayed-waveguide-grating demultiplexer and at least one receiving module. Each receiving module includes a multimode interference coupler and two output waveguides, the multimode interference coupler being located between the arrayed-waveguide-grating demultiplexer and the two output waveguides. The multimode interference coupler is configured to distribute, to the two output waveguides, an optical signal delivered by the arrayed-waveguide-grating demultiplexer. Such a device allows wavelength shifts in the signal delivered by a set of one or more sensors, in particular Bragg grating reflectors inscribed in a given optical fibre, to be measured. It allows a wavelength shift to be measured with a high linearity and a signal-to-noise ratio.

First claim

The invention claimed is:

1. A signal-distributing device for measuring at least one wavelength shift, and comprising an arrayed-waveguide-grating demultiplexer configured in order to spatially separate spectral contributions of an input optical signal, and at least one receiving module, each receiving module comprising a multimode interference coupler and two output waveguides, with the multimode interference coupler having a rectangular parallelopiped shape without a taper portion and located between the arrayed-waveguide-grating demultiplexer and the output waveguides and configured to distribute, to the two output waveguides, an optical signal originating from the arrayed-waveguide-grating demultiplexer, wherein said multimode interference coupler is attached directly against the arrayed- waveguide-grating demultiplexer and the output waveguides being directly attached to the coupler.

2. The device according to claim 1 , wherein in each receiving module, the respective ends of the two output waveguides are each located in a respective output zone of the multimode interference coupler, said output zones extending on either side of a plane of symmetry of the multimode interference coupler.

3. The device according to claim 2 , wherein in each receiving module, said output zones are symmetrical to each other relative to the plane of symmetry of the multimode interference coupler.

4. The device according to claim 2 , wherein in each receiving module, said output zones are each centred on a point located at a distance less than or equal to 1500 nm relative to a central axis of said multimode interference coupler .

5. The device according to claim 1 , wherein said device comprises a plurality of receiving modules disposed next to one another at the output of the arrayed-waveguide-grating demultiplexer.

6. The device according to claim 5 , wherein in each receiving module, respective ends of the two output waveguides are each located in a respective output zone of the multimode interference coupler, and wherein in each receiving module, a distance between a plane of symmetry of the multimode interference coupler and a similar plane in a directly neighbouring receiving module is greater than or equal to three times the distance between respective geometric centres of said output zones.

7. A system for measuring a wavelength shift, wherein said system comprises a signal-distributing device according to claim 1 , and at least one pair of photodetectors, each pair of photodetectors being associated with a respective receiving module of the signal-distributing device, and each photodetector of said pair being configured to receive a signal originating respectively from one of the two output waveguides of the corresponding receiving module.

8. The system according to claim 7 , wherein said system further comprises a computer configured to receive, as input, measurement signals supplied by at least one pair of photodetectors, and to supply as output, for each receiving module of the signal-distributing device, a measurement of a wavelength shift.

9. The system according to claim 8 , wherein for each pair of photodetectors, the computer is configured to calculate a ratio:

(

α
i
′

-

β
i
′

)

(

α
i
′

+

β
i
′

)

wherein α′ i designates the signal supplied by one of the photodetectors of said pair, and β′ i designates the signal supplied by the other of the photodetectors of said pair.

10. The system according to claim 7 , wherein said system further comprises at least one sensor optically coupled to the signal-distributing device, each sensor being configured to translate a parameter to be measured into a wavelength shift on a signal returned by said sensor, relative to a nominal wavelength of said sensor.

11. The system according to claim 10 , wherein a respective receiving module of the signal-distributing device corresponds to each sensor, and wherein in each receiving module the two output waveguides are configured to receive respective signals each centred on a respective wavelength, wherein said respective wavelengths frame the nominal wavelength of said sensor.

12. The system according to claim 10 , wherein said system further comprises an optical fibre within which a plurality of Bragg grating reflectors are inscribed, which each form a respective sensor optically coupled to the signal-distributing device.

13. A system for measuring a wavelength shift, comprising:
a signal-distributing device for measuring at least one wavelength shift, and comprising an arrayed-waveguide-grating demultiplexer configured in order to spatially separate spectral contributions of an input optical signal, and at least one receiving module, each receiving module comprising a multimode interference coupler and two output waveguides, with the multimode interference coupler located between the arrayed-waveguide-grating demultiplexer and the output waveguides and configured to distribute, to the two output waveguides, an optical signal originating from the arrayed-waveguide-grating demultiplexer, wherein said multimode interference coupler is attached directly against the arrayed-waveguide-grating demultiplexer or separated therefrom by a taper-type adapter,
at least one pair of photodetectors, each pair of photodetectors being associated with a respective receiving module of the signal-distributing device, and each photodetector of said pair being configured to receive a signal originating respectively from one of the two output waveguides of the corresponding receiving module, and
a computer configured to receive, as input, measurement signals supplied by at least one pair of photodetectors, and to supply as output, for each receiving module of the signal-distributing device, a measurement of a wavelength shift,
wherein for each pair of photodetectors, the computer is configured to calculate a ratio:

(

α
i
′

-

β
i
′

)

(

α
i
′

+

β
i
′

)

wherein α′ i designates the signal supplied by one of the photodetectors of said pair, and β′ i designates the signal supplied by the other of the photodetectors of said pair.

14. A system for measuring a wavelength shift, comprising:
a signal-di

Assignees

• Commissariat Energie Atomique
• Safran

Inventors

• Labeye Pierre
• Laffont Guillaume

Classifications

• G02B6/12019

  characterised by the optical interconnection to or from the AWG devices, e.g. integration or coupling with lasers or photodiodes (coupling integrated waveguide to fibre G02B6/30, to optoelectronic element G02B6/42; monolithic integration of integrated waveguides with other optical elements G02B6/12004) · CPC title

• G02B6/12016

  characterised by the input or output waveguides, e.g. tapered waveguide ends, coupled together pairs of output waveguides · CPC title

• G02B6/2746

  comprising non-reciprocal devices, e.g. isolators, FRM, circulators, quasi-isolators (magneto-optic non-reciprocal devices G02F1/093) · CPC title

• G02B6/2813

  based on multimode interference effect, i.e. self-imaging · CPC title

• G01D5/35316 Primary

  using a Bragg gratings · CPC title