Detection device and associated lidar system

Patent metadata

Field	Value
Publication number	US-12352863-B2
Application number	US-202117316600-A
Country	US
Kind code	B2
Filing date	May 10, 2021
Priority date	May 20, 2020
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A detection device for a coherent lidar imaging system includes an integrated detector comprising a matrix array of pixels distributed over N columns and M rows and comprising an optical guide, called reference guide, configured so as to receive a laser beam, called reference beam, N optical guides, called column guides, coupled to the reference guide, each column guide being coupled to M optical guides, called row guides, the M row guides being configured so as to route part of the reference beam into each pixel of the column, called pixel reference beam, each pixel of the integrated detector comprising: a guided photodiode coupled to an optical detection guide, a diffraction grating, called pixel grating, configured so as to couple a portion of a beam illuminating the pixel into the guided photodiode, a coupler, called pixel coupler, configured so as to couple the pixel coupled beam and at least a fraction of the pixel reference beam into the detection guide, an electronic readout and preprocessing circuit.

First claim

The invention claimed is:

1. A detection device for a coherent lidar imaging system comprising an integrated detector (Det) comprising a matrix array of pixels (Pi,j) distributed over N columns and M rows and comprising:
an optical guide, called reference guide (OGref), configured so as to receive a laser beam, called reference beam,
N optical guides (OGC(i)), called column guides, coupled to the reference guide, and designed to route part of the reference beam into the N columns of the detector,
each column guide being coupled to M optical guides (OGL(i,j)), called row guides, respectively associated with the M pixels of the M rows of the detector of said column, the M row guides being configured so as to route part of the reference beam into each pixel of the column, called pixel reference beam (Lref(i,j)), the coupling between the reference guide and the N column guides, as well as the coupling between each column guide and the M associated row guides, being passive,
each pixel (Pi,j) of the integrated detector comprising:
a guided photodiode (PhD(i,j)) coupled to an optical detection guide (OGD(i,j)),
a diffraction grating, called pixel grating (Rpix(i,j)), configured so as to couple a portion of a beam illuminating the pixel, called pixel coupled beam (Lo,rc(i,j)), into the guided photodiode,
a coupler, called pixel coupler (Coup(i,j)), configured so as to couple the pixel coupled beam and at least a fraction (Lref′(i,j)) of the pixel reference beam into the detection guide,

the guided photodiode thus being configured so as to receive said pixel coupled beam and at least said fraction (Lref′(i,j)) of the pixel reference beam,
an electronic circuit for readout and for preprocessing of a signal detected by the photodiode,

the preprocessing comprising amplification and filtering, wherein:
the pixel grating and the pixel coupler are two different components,
the row guide is connected to the pixel coupler, and
each pixel furthermore comprising a pixel waveguide (OGpix(i,j)) coupled upstream to the pixel grating and downstream to the pixel coupler and configured so as to route the pixel coupled beam to the pixel coupler.

2. The detection device according to claim 1 , furthermore comprising at least one electronic processing circuit configured so as to calculate, for each pixel, a frequency (F(i,j)) of a beat between the pixel reference beam and the pixel coupled beam.

3. The detection device according to claim 2 , wherein each pixel comprises its own electronic processing circuit (CE(i,j)) designed to calculate the beat frequency associated with the pixel.

4. The detection device according to claim 2 , wherein each column is connected to an electronic processing circuit (CC(i)) configured so as to calculate the beat frequency associated with each pixel of the column.

5. The detection device according to claim 1 , wherein the coupling between the reference guide and the N column guides, as well as the coupling between each column guide and the M associated row guides, is evanescent.

6. The detection device according to claim 1 , furthermore comprising:
a matrix array of transmissive deflecting elements (DE), a deflecting element being associated with a pixel or a group of pixels and configured so as to be able to be oriented individually by an electrical signal so as to deflect the one or more beams illuminating the one or more pixels,
each pixel or pixel group furthermore comprising a control loop (SL) associated with the deflecting element and configured so as to actuate the deflecting element so as to maximize a signal-to-noise ratio (SNR) of the detected signal generated by the guided photodiode.

7. The detection device according to claim 6 , wherein the deflecting element is chosen from a prism, a polyhedron, a spherical dome, and a diffractive optical element.

8. The detection device according to claim 6 , wherein a distance between the matrix array of deflecting elements and the integrated detector is between one and ten times a lateral dimension of the deflecting element.

9. The detection device according to claim 1 , furthermore comprising a matrix array of microlenses associated with the pixel matrix array, a microlens being configured so as to focus the beam illuminating the associated pixel on the pixel grating.

10. The detection device according to claim 1 , wherein the pixel coupler is a Y-junction.

11. A detection device for a coherent lidar imaging system comprising an integrated detector (Det) comprising a matrix array of pixels (Pi,j) distributed over N columns and M rows and comprising:
an optical guide, called reference guide (OGref), configured so as to receive a laser beam, called reference beam,
N optical guides (OGC(i)), called column guides, coupled to the reference guide, and designed to route part of the reference beam into the N columns of the detector,
each column guide being coupled to M optical guides (OGL(i,j)), called row guides, respectively associated with the M pixels of the M rows of the detector of said column, the M row guides being configured so as to route part of the reference beam into each pixel of the column, called pixel reference beam (Lref(i,j)), the coupling between the reference guide and the N column guides, as well as the coupling between each column guide and the M associated row guides, being passive,
each pixel (Pi,j) of the integrated detector comprising:
a guided photodiode (PhD(i,j)) coupled to an optical detection guide (OGD(i,j)),
a diffraction grating, called pixel grating (Rpix(i,j)), configured so as to couple a portion of a beam illuminating the pixel, called pixel coupled beam (Lo,rc(i,j)), into the guided photodiode,
a coupler, called pixel coupler (Coup(i,j)), configured so as to couple the pixel coupled beam and at least a fraction (Lref(i,j)) of the pixel reference beam into the detection guide,

the guided photodiode thus being configured so as to receive said pixel coupled beam and at least said fraction (Lref′ (i,j)) of the pixel reference beam,

an electronic circuit for readout and for preprocessing of a signal detected by the photodiode, the preprocessing comprising amplification and filtering, wherein:
the pixel grating is also the pixel coupler,
the pixel grating is coupled upstream to the row guide and downstream to the detection guide, so as to route said fraction of the pixel reference beam (Lref′ (i,j)) into the detection guide,
the pixel grating furthermore being configured so as to couple another fraction of the pixel reference beam, called pixel object beam (Lo(i,j)), into free space, in at least one direction opposite that of the beam illuminating the pixel.

12. A coherent lidar imaging system comprising:
a detection device according to claim 1 ,
at least one electronic processing circuit configured so as to calculate, for each pixel, a beat frequency (F(i,j)) of a beat between the pixel reference beam and the pixel coupled beam,
a laser source (SL) configured so as to emit laser radiation (L) having a temporally modulated optical frequency (FL),
a splitter device (LS) designed to spatially split the laser radiation (L) into a beam, called reference beam (Lref), and into a beam, called object beam (Lo), that is directed towards the scene to be observed (Obj),
a coupling device (CD) configured so as to couple the reference beam into the integrated detector,
an optical imaging system (Im) producing an image of the scene by focusing a beam reflected by the scene (Lo,r) on the detection device,
a processing unit (UT) connected to the integrated detector and to the laser source, the processing unit being configured so as to determine a distance of points

Assignees

• Commissariat Energie Atomique

Inventors

• Frey Laurent
• Daami Anis
• Fanget Stéphane

Classifications

• G02B6/4206

  Optical features (G02B6/4207, G02B6/421 take precedence) · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01S7/4814

  of transmitters alone · CPC title

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title

• G01S7/4917

  superposing optical signals in a photodetector, e.g. optical heterodyne detection · CPC title