Device for distributing a signal for measuring wavelength shifts

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-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,

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, and

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.

15. The device according to claim 1 , wherein

the arrayed-waveguide-grating demultiplexer has a planar guide element, and

the input face of the multimode interference coupler is attached to the planar guide element.