WO2023121888A1 - Télémétrie à l'aide d'un coupleur optique à trajet partagé - Google Patents

Télémétrie à l'aide d'un coupleur optique à trajet partagé Download PDF

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Publication number
WO2023121888A1
WO2023121888A1 PCT/US2022/052379 US2022052379W WO2023121888A1 WO 2023121888 A1 WO2023121888 A1 WO 2023121888A1 US 2022052379 W US2022052379 W US 2022052379W WO 2023121888 A1 WO2023121888 A1 WO 2023121888A1
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WIPO (PCT)
Prior art keywords
polarized light
polarization
multiplexer
outcoupler
guide
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PCT/US2022/052379
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English (en)
Inventor
Remus Nicolaescu
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Pointcloud Inc.
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Publication of WO2023121888A1 publication Critical patent/WO2023121888A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/126—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind using polarisation effects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/32—Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • G01S7/4812—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver transmitted and received beams following a coaxial path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/491—Details of non-pulse systems
    • G01S7/4912—Receivers
    • G01S7/4913—Circuits for detection, sampling, integration or read-out
    • G01S7/4914—Circuits for detection, sampling, integration or read-out of detector arrays, e.g. charge-transfer gates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/499—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using polarisation effects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/27—Optical coupling means with polarisation selective and adjusting means
    • G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
    • G02B6/2766—Manipulating the plane of polarisation from one input polarisation to another output polarisation, e.g. polarisation rotators, linear to circular polarisation converters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12083—Constructional arrangements
    • G02B2006/12107—Grating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12083—Constructional arrangements
    • G02B2006/12123—Diode
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
    • G02B6/4213—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms the intermediate optical elements being polarisation selective optical elements

Definitions

  • the present disclosure generally relates to photonic integrated circuits for receiving and transmitting light.
  • Optical ranging systems can bounce light off an object and ascertain the object’s distance by comparing the transmitted and reflected light.
  • Conventional optical ranging systems are large unwieldly systems that require many parts. Such systems can be difficult to integrate into real world applications, such as autonomous vehicle object detection systems.
  • FIG. 1 illustrates a block diagram of a monolithic pixel using a dual polarization outcoupler (e.g., an output coupler, such as a bidirectional output coupler) and a polarization multiplexer, according to some example embodiments.
  • a dual polarization outcoupler e.g., an output coupler, such as a bidirectional output coupler
  • a polarization multiplexer e.g., a polarization multiplexer
  • FIG. 2 illustrates a monolithic pixel using a dual polarization outcoupler and an evanescent coupling polarization multiplexer, according to some example embodiments.
  • FIG. 3 illustrates another monolithic pixel using a dual polarization outcoupler and an evanescent coupling polarization multiplexer, according to some example embodiments.
  • FIG. 4 illustrates a monolithic pixel using a dual polarization outcoupler and a grating-assisted polarization multiplexer, according to some example embodiments.
  • FIG. 5 illustrates a row of pixels each using a dual polarization outcoupler and polarization multiplexer within each pixel and a polarization rotator per row with a shared signal and local oscillator bus, according to some example embodiments.
  • FIG. 6 illustrates a two dimensional array of pixels using a dual polarization outcoupler and a polarization multiplexer within each pixel and polarization rotator at the end of the row, according to some example embodiments.
  • FIG. 7 illustrates an integrated system on a chip imaging array using a dual polarization outcoupler and polarization multiplexer within the pixel and polarization rotator at the end of the row or row section, according to some example embodiments.
  • FIG. 8 illustrates integrated, complete system on a chip using a dual polarization outcoupler and polarization multiplexer within the pixel and polarization rotator at the end of the row or row section, according to some example embodiments.
  • FIG. 9 illustrates a three dimensional imaging camera based on an integrated, complete system on a chip using a dual polarization outcoupler and polarization multiplexer within the pixel and polarization rotator at the end of the row or row section and used in a focal plane array configuration, according to some example embodiments.
  • FIG. 10 illustrates the block diagram comprising key components of a three dimensional imaging system based on an integrated coherent imaging array, according to some example embodiments.
  • FIG. 11 illustrate one embodiment of a pixel architecture using a dual polarization outcoupler, an evanescent coupler based polarization multiplexer and a polarization rotator in each pixel, according to some example embodiments.
  • FIG. 12 illustrates one embodiment of a row of pixels, each pixel using a dual polarization outcoupler, an evanescent coupler based polarization multiplexer and a polarization rotator in each pixel in a monostatic configuration, according to some example embodiments.
  • FIG.13 illustrates one embodiment of a two dimensional array of pixels, each pixel using a dual polarization outcoupler, an evanescent coupler based polarization multiplexer and a polarization rotator in each pixel in a monostatic configuration, according to some example embodiments.
  • FIG.14 illustrates one embodiment of an integrated three dimensional imaging system using and array of pixels, each pixel using a dual polarization outcoupler, an evanescent coupler based polarization multiplexer and a polarization rotator in each pixel in a monostatic configuration, according to some example embodiments.
  • FIG. 15 illustrates one embodiment of an outcoupler using internal reflection to direct light through the backside of the wafer, according to some example embodiments.
  • FIG. 16 illustrates one embodiment of an outcoupler using internal reflection to direct light through the front of the wafer, according to some example embodiments.
  • FIG. 17 illustrates one embodiment of an outcoupler using a diffraction grating to direct light through the front side of the wafer, according to some example embodiments.
  • FIG. 18 illustrates one embodiment of an outcoupler using a diffraction grating and reflection by a layer in the stack to direct light through the backside of the wafer, according to some example embodiments.
  • FIG. 19 illustrates one embodiment of a pixel architecture using a dual polarization outcoupler, and a bent directional coupler polarization splitter rotator, according to some example embodiments.
  • FIG. 20 illustrates one embodiment of a pixel architecture using a dual polarization outcoupler, and a bent directional coupler polarization splitter rotator and a thin film Faraday rotator, according to some example embodiments.
  • Some example embodiments involve the field of light detection and ranging (LIDAR) 3D imaging and more specifically can involve the creation of accurate 3D coordinates and velocity maps of environments, objects, or living entities as needed for autonomous navigation, object recognition applications (such as surveillance), robotic manipulation, augmented reality, or vital signs monitoring of living entities for health and wellbeing monitoring and diagnostics.
  • LIDAR light detection and ranging
  • Two approaches for measuring the coordinates of a remote target and creating a 3D image of an object or environment include: (1) one based on a time-of-flight approach, in which measurements of the roundtrip time of a short pulse or pulse succession emitted by a laser are converted to a 3D map, and (2) a second based on a continuous wave frequency modulation approach, in which phase or frequency of a laser source transmitter can be modulated, and the phase or frequency shift in the target scattered signal with respect to the original signal can be measured to determine distance.
  • Some conventional implementations implement the time-of- flight approach with amplitude modulation due to an abundance of nanosecond-pulse-length high-peak-power laser sources and the simplicity and large number of options to implement such a system.
  • Examples of conventional approaches include: a rotating head with mechanically fixed laser/detector pairs all rotating with the head assembly, approaches in which the scanning of the beam can be accomplished using a micro-electrical-mechanical system (MEMS) mirror, a galvo mirror, or rotating prisms, and other optomechanical scanning solutions coupled with the use of one or multiple high-speed high-gain avalanche photodetectors.
  • MEMS micro-electrical-mechanical system
  • galvo mirror galvo mirror
  • rotating prisms or rotating prisms
  • optomechanical scanning solutions coupled with the use of one or multiple high-speed high-gain avalanche photodetectors.
  • One disadvantage of these approaches is the large number of discrete parts required, which leads to a high cost of manufacturing and low reliability due to their moving parts.
  • One further approach includes a detector array with single photon detection sensitivity, and a solid state transmitter that provides flash or sequential flash illumination of the target object.
  • One disadvantage of such a system is its high cost, limited range, limited accuracy, and limited scalability for such an approach.
  • One further approach includes a time-gated silicon-based detector array or sensors, such as Texas Instruments and STMicroelectronics sensors, and is based on an indirect time-of- flight measurement.
  • One disadvantage for these types of sensors is that they are limited to very short distances (generally up to 3 m), resolution is typically low (e.g., in the range of several centimeters), and they are strongly affected by ambient light.
  • One further approach includes a coherent nanophotonic imager that implements chirped frequency amplitude modulation.
  • the coherent nanophotonic approach uses a phase control mechanism that is difficult to implement for the small number of pixels typically used for a short range configuration. Accurate phase control is important in such an implementation, and it is difficult to maintain in a non-laboratory setting. In addition, scaling such a system has not been demonstrated.
  • One aspect of 3D imaging systems that enables longer- range high-resolution systems may include the ability to control the shape of the outgoing optical beam.
  • a short-range system using a focal plane array on the receiver side one can use a wide- angle illumination of the entire scene to be captured.
  • the desired range increases, in order to receive enough scattered photons on each pixel of the focal plane array, it becomes important to reduce the divergence of the outgoing beam and therefore increase the intensity on the surface of the target object.
  • the ability to dynamically shape and scan the optical beam over the surface of the target object’s landscape may be beneficial.
  • a two-dimensional scanning mirror which scans a low divergence (e.g., collimated) beam over the landscape, the mirrors being either macroscopically driven by piezo drives or by a MEMS
  • an optical phased array of micro antennas where the shaping and direction of the optical signal can be controlled by adjusting the phase or wavelength of the outbound signals in each of the antennas in the array
  • a sequential flash approach where small portions of the target object are sequentially illuminated by an array of emitters.
  • Mirrorbased approaches may suffer from speed and reliability problems, while optical phased arrays have been technologically very difficult to implement for optical domain electromagnetic waves.
  • receiver focal plane arrays can be combined with a steering mechanism of a collimated beam generated by a transmitter focal plane array of out-couplers sequentially emitting towards the target object and used for scanning the target area of the target object, which allows for the advantages of both receiver focal plane arrays and the high intensity on the target for achieving long range.
  • simultaneous illumination of several pixels and readout in parallel is desirable.
  • the transmit and receive paths are not shared.
  • the two arrays should be precisely aligned in order for the imaging of the transmitter array of outcouplers to precisely overlap with the receiver array of outcouplers.
  • the transmitter beams should be kept as collimated as possible in order to maintain maximum intensity of illumination on the target object, and such a requirement may make a system composed of the two arrays very sensitive to misalignment.
  • a system in which the outbound and inbound paths are overlapping and the same coupler is used to couple light in and out of the chip may therefore be desirable, as such a system would eliminate any alignment issues and, as a consequence, eliminate or reduce risks of manufacturing inaccuracies that would result in reduced efficiency.
  • a ranging architecture that improves upon the efficiency of separate path focal plane arrays can be implemented by using a shared path pixel architecture replicated in a two- dimensional array, according to some example embodiments.
  • the single path architecture illuminates only those parts of the target object which correspond to the field of view of the individual pixel.
  • the spots on the target object to be imaged that correspond to the active area of the pixels are illuminated by the transmitter beam, high intensity in the transmitter beam can be maintained, and the overall efficiency of the system is improved.
  • the loss of efficiency due to manufacturing and misalignment was traded for a 3 dB fundamental loss using a transverse mode multiplexer pixel architecture.
  • a further improvement in efficiency, eliminating the 3 dB fundamental loss and ensuring that no light is wasted, may be implemented using a polarization multiplexing pixel architecture.
  • the principle of operation of a pixel using a single outcoupler and a polarization multiplexer in each pixel is illustrated in FIG. 1.
  • light in transverse electric (TE) polarization is guided into the pixel through a waveguide 101, is transmitted through a polarization multiplexer 102, and exits the photonic integrated circuit (PIC) thorough an outcoupler 103.
  • TE transverse electric
  • PIC photonic integrated circuit
  • TM polarization Light exiting the chip through the outcoupler 103 in TE polarization passes through a polarization rotator 104, which rotates the polarization by 45 degrees and is directed towards the target object. Light scattered by the target object propagates back and passes through the polarization rotator 104, which converts the light into transverse magnetic (TM) polarized light, which is then coupled into the plane of the PIC by the outcoupler 103. Light in TM polarization is directed through the polarization multiplexer 102 towards a 2x2 multiplexer 105 where it is mixed with local oscillator light, also in TM polarization, and the combined signal is detected by a balanced detector 107.
  • TM transverse magnetic
  • FIG. 1 Different embodiments for the implementation of the pixel described in the block diagram in Figure 1 are shown in Figure 2, Figure 3, and Figure 4, whose embodiments show different implementations for the polarization multiplexer 102 using one or more bent waveguide couplers or grating assistance.
  • the embodiments illustrated in Figures 1-4 have the advantage of reducing the back reflection from the outcoupler 103 into the very sensitive balanced heterodyne detector 107, as the back reflected light which is in TE polarization is directed through the polarization multiplexer 102 into the input waveguide 101, instead of the input of the 2x2 multiplexer 105 and then the heterodyne detector 107.
  • the polarization multiplexer 102 serves the function of optical isolation for the heterodyne detector 107, in addition to the multiplexing of the outbound TE with the inbound TM polarizations.
  • Figure 5 illustrates one embodiment for a row of pixels.
  • one input waveguide is used to direct into the pixel the TE polarized signal as well as a TM polarized local oscillator.
  • Light provided by waveguide 200 is distributed to N pixels using tap couplers 201.
  • the tap couplers couple into each successive pixel a progressively higher percentage of the input light such that all pixels in the row receive a substantially equal amount of light.
  • the residual light from the waveguide 200 in TE polarization is directed into the input of a polarization rotator 203, which rotates the polarization to TM polarized light.
  • TM polarized light exiting the polarization rotator 203 is used to provide a local oscillator for each of the N pixels.
  • the distribution of the local oscillator light to the N pixels is accomplished by the progressively larger coupling strength tap couplers 204.
  • the number of pixels N is 8, and the input power in the row is 90 mW, such that each of the 8 pixels receives 10 mW of laser power using the progressively higher strength tap couplers, with 10 mW of remaining residual light at the input of the polarization rotator 203.
  • the 10 mW of residual TE polarized light at the input of the polarization rotator 203 is rotated into TM polarization and distributed in substantially equal amounts of 1.25 mW to each of the 8 pixels in the row.
  • Figure 6 illustrates one embodiment of a two-dimensional imaging array of pixels 300.
  • Figure 7 illustrates one embodiment of a single-chip three-dimensional imaging device 400.
  • Frequency modulated light is input into the optical switch 402 including the switch control electronics 403.
  • the optical switch 402 directs light sequentially to rows of the imaging array 300.
  • the integrated imaging system 400 comprises the imaging array 300, the electronic readout 401, the optical switch 402, and the switch electronics 403.
  • a three- dimensional imaging chip 500 comprises an imaging array 300, an optical switch 402, and an optical frequency modulated signal generator 501, all integrated monolithically or using hybrid integration on the same substrate.
  • a lens 602 is used to image the target object 603 onto the imaging array 601.
  • a three- dimensional imaging system 700 is assembled from a photonics integrated circuit 500, laser light sources 803, a signal processor 801 to process the signal generated by photonics integrated circuit 500, and an ensemble of laser and optical amplifier drivers, power management, and other electronic integrated circuits.
  • the outcoupler 103 may be a diffraction grating, an edge coupler, an internal reflection mirror, a metal mirror, or a dielectric mirror. In one embodiment, the outcoupler 103 may direct light towards the front or the back of the semiconductor material wafer.
  • the polarization rotator 908 is incorporated into the pixel architecture.
  • signal in TE polarization enters the pixel 900 through a waveguide 901.
  • the majority of the optical signal propagates towards the first port of a polarization multiplexer 903, exits the polarization multiplexer 903 through the second port and exits the chip through an outcoupler 904.
  • the outbound optical signal in TE polarization propagates towards a target object, passes through a Faraday rotator 905, is scattered by the target object, and passes a second time in the opposite direction through the Faraday rotator 905, and the return TM polarized light is coupled back into the chip through the outcoupler 904.
  • the return signal in TM polarization, coupled back into the outcoupler 904, is directed to the second port of the polarization multiplexer 903, which directs the TM polarized light towards the third port of the polarization multiplexer 903 and further towards an input into the 2x2 multiplexer 907.
  • TE polarized light tapped from the input waveguide 901 with the help of a tap coupler 902 has its polarization rotated by the polarization rotator 908 into TM polarized light. In this manner, the two inputs of the 2x2 multiplexer 907 are both in the same polarization, and hence they may interfere and create a beat note.
  • the outcoupler 904 may be a diffraction grating, an edge coupler, an internal reflection mirror, a metal mirror, or a dielectric mirror. In one embodiment, the outcoupler 904 may direct light towards the front or the back of the semiconductor material wafer. Several embodiments of outcouplers are illustrated in Figures 15-18. In one embodiment illustrated in Figure 15, internal reflection is used to direct the optical signal propagating through waveguide 1301 and direct it towards the back of the silicon photonics wafer through the buried oxide layer 1302 and silicon substrate layer 1303. In one embodiment, an additional antireflection coating may be deposited on the backside of the wafer to reduce back reflections and losses for the transmitted beam.
  • internal reflection is used to direct the optical signal propagating through waveguide 1301 and direct it towards the front of the silicon photonics wafer through the oxide layer 1400.
  • an additional antireflection coating may be deposited on the front of the wafer to reduce back reflections and losses for the transmitted beam.
  • the angled facet needed to achieve internal reflection may be created using an anisotropic wet etch with etch rates determined by the crystallographic directions of the semiconductor material.
  • the outcoupler is a grating coupler 1502 that directs out of the plane and towards the front side of the silicon on insulator wafer the optical signal propagating through waveguide 1501.
  • light emitted by a grating outcoupler 1602 is reflected by metal layer 1603 and directed through the buried oxide layer 1604 and substrate 1605 to exit through the backside of the wafer.
  • an anti-reflection coating may be used on the backside of the wafer to minimize back reflections and improve transmission of the optical signal.
  • the outcoupler for the pixels described in Figures 1-4 or other pixel architectures may be grating couplers, total internal emission couplers, emitting through the front or backside of the wafer, or edge couplers, emitting thought the edge of the photonics integrated circuit.
  • signal in TE polarization enters the pixel 1700 through waveguide 1701.
  • the majority of the optical signal propagates towards the first port of polarization splitter-rotator 1703, exits the polarization splitterrotator 1703 through the second port and exits the chip through outcoupler 1704 in TE polarization.
  • the outbound optical signal in TE polarization propagates towards target, passes through Faraday rotator 1705 which rotates the polarization by 45 degrees, is scattered by the target and passes a second time in the opposite direction through Faraday rotator 1705 for a second 45 degrees rotation, the double pass having, as an effect, the rotation from TE to TM polarization.
  • the return TM polarized light is coupled back into the chip through outcoupler 1704. It propagates from the outcoupler 1704 to the second port of polarization splitter rotator 1703 and then through polarization splitter-rotator 1703 to the third port of 1703 and further into one of the two inputs into the 2x2 multiplexer 1707.
  • Light exiting the polarization splitterrotator 1703 in TE polarization is mixed by 2x2 multiplexer 1707 with local oscillator light in TE polarization tapped through the tap 1702 and guided by waveguide 1706 into the second input of the multiplexer 1707.
  • Mixed local oscillator and return signal light is detected by detectors 1708 that will detect the difference in frequency between the return signal and the local oscillator light.
  • the polarization splitter rotator 1703 may be based on an asymmetrical directional couplers, bi-layer tapers, Y junctions, multimode interference waveguides or partially etched sub wavelength grating couplers.
  • the polarization beamsplitter within the pixel may use a coupler design configuration which exploits the difference in the phase between the TE and TM modes in silicon waveguides to achieve the phase matching condition for light propagating in two waveguides for one polarization while not in the other.
  • the polarization beamsplitter that is part of the pixel may use a slotted waveguide combined with an asymmetric waveguide design.
  • one or more of the embodiments presented in Figures 1-20 may be implemented using a silicon photonics material system including silicon, silicon oxide and nitride layers, a group III and group V material system or another semiconductor or dielectric based material stack.
  • one or more of the embodiments presented in Figures 1-20 may be implemented using a wavelength of light in the interval from 1300 nm to 1600 nm though other wavelengths may be used.
  • one or more of the embodiments presented in Figures 1-20 may be used to measure the x, y, and z coordinates of a target as well as the radial velocity and reflectivity for each point.
  • the Faraday rotator 104, 905 or 1705 may be a thin film Faraday rotator, deposited directly on the wafer either on the front of the wafer in the case of a front side illuminated architecture or on the back side for a back side illuminated architecture.
  • signal in TE polarization enters the pixel 1800 through waveguide 1801.
  • the majority of the optical signal propagates towards the first port of polarization splitter-rotator 1803, exits the polarization splitterrotator 1803 through the second port passes through thin film Faraday rotator 1804 which rotates polarization by 45 degrees and exits the chip through outcoupler 1805.
  • the outbound optical signal propagates towards target, is scattered by the target and is coupled back into the chip through outcoupler 1805. From outcoupler 1805 it propagates through thin film Faraday rotator 1804 where the polarization is rotated by a further 45 degrees.
  • the light in TM polarization propagates to the second port of polarization splitter rotator 1803 and then through polarization splitter-rotator 1803 to the third port of 1803 and further into one of the two inputs into the 2x2 multiplexer 1807.
  • Light exiting the polarization splitter-rotator 1803 in TE polarization is mixed by 2x2 multiplexer 1807 with local oscillator light in TE polarization tapped through the tap 1802 and guided by waveguide 1806 into the second input of the multiplexer 1807.
  • Mixed local oscillator and return signal light is detected by detectors 1808 that will detect the difference in frequency between the return signal and the local oscillator light.
  • a first example provides a photonic integrated circuit comprising: a waveguide configured to receive and guide transverse electric polarized light; a polarization multiplexer configured to receive the transverse electric polarized light from the waveguide and guide the transverse electric polarized light towards an object; and an outcoupler configured to send the transverse electric polarized light towards the object, receive transverse magnetic polarized light, and guide the transverse magnetic polarized light toward the polarization multiplexer, the polarization multiplexer being further configured to guide the transverse magnetic polarized light towards a detector.
  • a second example provides a photonic integrated circuit according to the first example, wherein: the polarization multiplexer is configured to guide the transverse electric polarized light arriving from the waveguide toward the outcoupler differently from guiding the transverse magnetic polarized light arriving from the outcoupler toward the detector.
  • a third example provides example provides a photonic integrated circuit according to the first example or the second example, wherein: the outcoupler is configured to send the transverse electric polarized light arriving from the polarization multiplexer out toward the object and guide the transverse magnetic polarized light arriving from the object in toward the polarization multiplexer.
  • a fourth example provides a photonic integrated circuit according to any of the first through third examples, wherein: the outcoupler is configured to send the transverse electric polarized light from the polarization multiplexer through a polarization rotator toward the object; and the polarization rotator is configured to provide the outcoupler with the transverse magnetic polarized light by rotating a polarization of light reflected back from the object.
  • a fifth example provides a photonic integrated circuit according to the fourth example, further comprising: the polarization rotator, configured to rotate a polarization of the transverse electric polarized light from the outcoupler and to provide the outcoupler with the transverse magnetic polarized light by rotating the polarization of the light reflected back from the object.
  • a sixth example provides a photonic integrated circuit according to any of the first through fifth examples, further comprising: a further multiplexer configured to guide the transverse magnetic polarized light from the polarization multiplexer to the detector.
  • a seventh example provides a photonic integrated circuit according to the sixth example, wherein: the polarization multiplexer is configured to guide the transverse magnetic polarized light from the outcoupler to the further multiplexer that is coupled to the detector.
  • An eighth example provides a photonic integrated circuit according to the sixth example or the seventh example, wherein: the further multiplexer is configured to receive local oscillator light and provide a mixture of the local oscillator light and the transverse magnetic polarized light from the polarization multiplexer to the detector.
  • a ninth example provides a photonic integrated circuit according to the eighth example, wherein: the waveguide configured to receive and guide the transverse electric polarized light is a first waveguide; and the photonic integrated circuit further comprises: a second waveguide configured to receive additional transverse magnetic polarized light and guide the additional transverse magnetic polarized light to the further multiplexer.
  • a tenth example provides a photonic integrated circuit according to the ninth example, wherein: the further multiplexer is configured to provide local oscillator light by providing the additional transverse magnetic polarized light received from the second waveguide.
  • An eleventh example provides a method comprising: providing, in a photonic integrated circuit, a waveguide configured to receive and guide transverse electric polarized light; providing, in the photonic integrated circuit, a polarization multiplexer configured to receive the transverse electric polarized light from the waveguide and guide the transverse electric polarized light towards an object; and providing, in the photonic integrated circuit, an outcoupler configured to send the transverse electric polarized light towards the object, receive transverse magnetic polarized light, and guide the transverse magnetic polarized light toward the polarization multiplexer, the polarization multiplexer being further configured to guide the transverse magnetic polarized light towards a detector.
  • a twelfth example provides a method according to the eleventh example, wherein: the polarization multiplexer is configured to guide the transverse electric polarized light arriving from the waveguide toward the outcoupler differently from guiding the transverse magnetic polarized light arriving from the outcoupler toward the detector.
  • a thirteenth example provides a method according to the eleventh example or the twelfth example, wherein: the outcoupler is configured to send the transverse electric polarized light arriving from the polarization multiplexer out toward the object and guide the transverse magnetic polarized light arriving from the object in toward the polarization multiplexer.
  • a fourteenth example provides a method according to any of the eleventh through thirteenth examples, wherein: the outcoupler is configured to send the transverse electric polarized light from the polarization multiplexer through a polarization rotator toward the object; and the polarization rotator is configured to provide the outcoupler with the transverse magnetic polarized light by rotating a polarization of light reflected back from the object.
  • a fifteenth example provides a method according to the fourteenth example, further comprising: providing, in the photonic integrated circuit, the polarization rotator configured to rotate a polarization of the transverse electric polarized light from the outcoupler and to provide the outcoupler with the transverse magnetic polarized light by rotating the polarization of the light reflected back from the object.
  • a sixteenth example provides a method according to any of the eleventh through fifteenth examples, further comprising: providing, in the photonic integrated circuit, a further multiplexer configured to guide the transverse magnetic polarized light from the polarization multiplexer to the detector.
  • a seventeenth example provides a method according to the sixteenth example, wherein: the polarization multiplexer is configured to guide the transverse magnetic polarized light from the outcoupler to the further multiplexer that is coupled to the detector.
  • An eighteenth example provides a method according to the sixteenth example or the seventeenth example, wherein: the further multiplexer is configured to receive local oscillator light and provide a mixture of the local oscillator light and the transverse magnetic polarized light from the polarization multiplexer to the detector.
  • a nineteenth example provides a method according to the eighteenth example, wherein: the waveguide configured to receive and guide the transverse electric polarized light is a first waveguide; and the method further comprises: providing, in the photonic integrated circuit, a second waveguide configured to receive additional transverse magnetic polarized light and guide the additional transverse magnetic polarized light to the further multiplexer.
  • a twentieth example provides a method according to the nineteenth example, wherein: the further multiplexer is configured to provide local oscillator light by providing the additional transverse magnetic polarized light received from the second waveguide.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un appareil et des procédés qui fournissent un circuit intégré photonique et son fonctionnement. Le circuit intégré photonique peut comprendre un guide d'ondes configuré pour recevoir et guider une lumière polarisée électrique transversale, un multiplexeur de polarisation configuré pour recevoir la lumière polarisée électrique transversale provenant du guide d'ondes et guider la lumière polarisée électrique transversale vers un objet, et un coupleur de sortie configuré pour envoyer la lumière polarisée électrique transversale vers l'objet, recevoir une lumière polarisée magnétique transversale, et guider la lumière polarisée magnétique transversale vers le multiplexeur de polarisation, le multiplexeur de polarisation pouvant être en outre configuré pour guider la lumière polarisée magnétique transversale vers un détecteur.
PCT/US2022/052379 2021-12-23 2022-12-09 Télémétrie à l'aide d'un coupleur optique à trajet partagé WO2023121888A1 (fr)

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US63/265,972 2021-12-23

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100119229A1 (en) * 2007-04-05 2010-05-13 Imec Method and system for multiplexer waveguide coupling
US20210382142A1 (en) * 2020-06-08 2021-12-09 Pointcloud Inc. Microlens array lidar system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100119229A1 (en) * 2007-04-05 2010-05-13 Imec Method and system for multiplexer waveguide coupling
US20210382142A1 (en) * 2020-06-08 2021-12-09 Pointcloud Inc. Microlens array lidar system

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