Abstract: Aspects of the disclosure provide a system and method used for time-of-flight lidar applications. Such systems and methods include a laser and pulse clipper which produces a shuttering effect to reduce the instantaneous output power from the pulse clipper. Accordingly the output from the pulse clipper is more suitable for time-of-flight lidar applications than that initially produced by the laser. This can allow for lasers which may otherwise exceed eye safety limits to be used for time-of-flight lidar applications without exceeding the eye safety limits.

Abstract: An optical performance monitor comprises a first stage configured to receive a multiplexed optical signal. The first stage is tunable over a period. The first stage periodically filters the multiplexed optical signal over an optical channel to produce a fine filtered optical signal. A second stage is coupled to the first stage and has a second-stage transfer function. The second stage receives the fine filtered optical signal and produces one or a plurality of interfered optical signal pairs. A third stage is coupled to the second stage and has a third-stage transfer function. The third stage receives the optical signal pairs and demultiplexes the optical signal pairs to produce a plurality of demultiplexed optical signals. The combination of the second-stage transfer function and the third-stage transfer function is flatter over the optical channel than the third-stage transfer function.

Abstract: A LIDAR includes multiple light sources and a Liquid Crystal on Silicon (LCOS) device for controllably redirecting beams from each of the multiple light sources. The same or a different LCOS device can be used to controllably redirect reflected light to each of several corresponding light detectors. The LCOS device can be adjusted on a slower time scale while the light sources can be sequentially activated on a faster time scale. The LCOS device provides for fine steering control of LIDAR beams. The use of multiple light sources and detectors allows for a higher LIDAR scan rate.

Abstract: A coherent LIDAR method and apparatus are provided, in which two optical signals having a first frequency difference are reflected by an object. A difference in frequency between the corresponding received and reflected signals is determined. The frequency difference between the reflected signals differs from the first frequency difference due to Doppler effects. The object velocity is determined based on a comparison between the first frequency difference and the frequency difference in the reflected signals. The emitted signals can be produced by modulating a common light source. The reflected signals are inherently mixed at the receiver and further processed. Distance to the object can be determined by pulsing the emitted signals and measuring a time of flight by detecting corresponding pulse edges in the reflected signals, or by using phase sweeping. The emitter can be implemented using an optical phased array.

Abstract: An optical performance monitor comprises a first stage configured to receive a multiplexed optical signal. The first stage is tunable over a period. The first stage periodically filters the multiplexed optical signal over an optical channel to produce a fine filtered optical signal. A second stage is coupled to the first stage and has a second-stage transfer function. The second stage receives the fine filtered optical signal and produces one or a plurality of interfered optical signal pairs. A third stage is coupled to the second stage and has a third-stage transfer function. The third stage receives the optical signal pairs and demultiplexes the optical signal pairs to produce a plurality of demultiplexed optical signals. The combination of the second-stage transfer function and the third-stage transfer function is flatter over the optical channel than the third-stage transfer function.

Abstract: A photonic integrated circuit is provided that is adapted to compensate for an unintentional manufactured refractive index profile, such as a gradient, that arises due to manufacturing variance. The photonic integrated circuit including at least a thermal source and a spaced thermal sink to induce a thermal gradient in the photonic integrated circuit between the thermal source and the spaced thermal sink, the thermal gradient imparts an opposing thermal refractive index profile to correct for the manufactured refractive index profile. In some embodiments the photonic integrated circuit may be constructed with features that have an intentional structured refractive index profile that ensures any unintentional manufactured refractive index profile is correctable by the opposing thermal refractive index profile induced by the thermal source.

Abstract: The present invention provides a photonic device such as a variable optical attenuator, in which two signal components, propagating in modes of two different polarization states, are converted to two different modes of the same polarization state prior to modulation. The modulation of both components is performed by a single device which applies the same modulation strength to both components. The two signal components can be converted back to propagate in the two different polarization states following modulation.

Abstract: A photonic platform includes a substrate, a buried oxide layer on the substrate, a first optical layer on the buried oxide layer, the first optical layer including one or more waveguides shaped as rib waveguides protruding upwardly from a common underlying slab and a second optical layer spaced above the first optical layer, the second optical layer defining an upper waveguide that crosses over the one or more partially etched waveguides. A low-loss photonic switch may be made using a silicon photonic platform implementing this waveguide crossing.

Abstract: A LIDAR or other optical beamsteering apparatus includes an optical switch having a first port and a plurality of second ports. The switch is operated to establish an optical path between the first port and one of the second ports. The first port is connected to a light source or a light detector. Different second ports are connected to different surface/edge couplers. Each of the surface/edge couplers couples light from or to the apparatus in a different respective direction. The surface/edge couplers can be grating couplers. The direction of light coupling is configured due to the orientation of the surface/edge coupler and its grating period, where applicable. Surface/edge couplers can be arranged in a circular or concentric ring pattern. Grating couplers can be elongated.

Abstract: A photonic integrated circuit is provided that is adapted to compensate for an unintentional manufactured refractive index profile, such as a gradient, that arises due to manufacturing variance. The photonic integrated circuit including at least a thermal source and a spaced thermal sink to induce a thermal gradient in the photonic integrated circuit between the thermal source and the spaced thermal sink, the thermal gradient imparts an opposing thermal refractive index profile to correct for the manufactured refractive index profile. In some embodiments the photonic integrated circuit may be constructed with features that have an intentional structured refractive index profile that ensures any unintentional manufactured refractive index profile is correctable by the opposing thermal refractive index profile induced by the thermal source.

Abstract: A time-of-flight apparatus includes a transmitter and a receiver. The transmitter includes a laser for providing a laser pulse and an optical phased array coupled to the laser for receiving the laser pulse and providing a plurality of beams which fan out from the optical phased array. The receiver includes an optical receiving unit for receiving scattered light from the plurality of beams and a photodetector array coupled to the optical receiving unit. The photodetector array includes a plurality of photodetectors such that at least one particular photodetector of the photodetector array is disposed for receiving scattered light from each particular beam of the plurality of beams.

Abstract: An optical waveguide termination comprising a light-receiving inlet for receiving light to be terminated, a curved section extending from the inlet and having a continuously decreasing radius of curvature, and a light-terminating tip at an end of the curved section. The curved section may define a spiral waveguide, for example a logarithmic spiral, having a waveguide width that continuously decreases from the inlet to the tip.

Abstract: Aspects of the disclosure provide a system and method used for time-of-flight lidar applications. Such systems and methods include a laser and pulse clipper which produces a shuttering effect to reduce the instantaneous output power from the pulse clipper. Accordingly the output from the pulse clipper is more suitable for time-of-flight lidar applications than that initially produced by the laser. This can allow for lasers which may otherwise exceed eye safety limits to be used for time-of-flight lidar applications without exceeding the eye safety limits.

Abstract: A LIDAR or other optical beamsteering apparatus includes an optical switch having a first port and a plurality of second ports. The switch is operated to establish an optical path between the first port and one of the second ports. The first port is connected to a light source or a light detector. Different second ports are connected to different surface/edge couplers. Each of the surface/edge couplers couples light from or to the apparatus in a different respective direction. The surface/edge couplers can be grating couplers. The direction of light coupling is configured due to the orientation of the surface/edge coupler and its grating period, where applicable. Surface/edge couplers can be arranged in a circular or concentric ring pattern. Grating couplers can be elongated.

Abstract: A LIDAR includes multiple light sources and a Liquid Crystal on Silicon (LCOS) device for controllably redirecting beams from each of the multiple light sources. The same or a different LCOS device can be used to controllably redirect reflected light to each of several corresponding light detectors. The LCOS device can be adjusted on a slower time scale while the light sources can be sequentially activated on a faster time scale. The LCOS device provides for fine steering control of LIDAR beams. The use of multiple light sources and detectors allows for a higher LIDAR scan rate.

Abstract: A coherent LIDAR method and apparatus are provided, in which two optical signals having a first frequency difference are reflected by an object. A difference in frequency between the corresponding received and reflected signals is determined. The frequency difference between the reflected signals differs from the first frequency difference due to Doppler effects. The object velocity is determined based on a comparison between the first frequency difference and the frequency difference in the reflected signals. The emitted signals can be produced by modulating a common light source. The reflected signals are inherently mixed at the receiver and further processed. Distance to the object can be determined by pulsing the emitted signals and measuring a time of flight by detecting corresponding pulse edges in the reflected signals, or by using phase sweeping. The emitter can be implemented using an optical phased array.

Abstract: An optical waveguide termination includes a light-receiving inlet for receiving light to be terminated, a rib waveguide extending from the inlet, a doped, light-absorbing slab supporting the rib waveguide for absorbing light from the rib waveguide, and a tip at an end of the rib waveguide. The optical waveguide termination exhibits low back-reflection.

Abstract: A photonic platform based polarization controller providing a fixed target polarization is disclosed. The polarization controller has a polarization rotator splitter splitting the beam into first and second feeds corresponding to first and second orthogonal polarization components. A first Mach-Zehnder interferometer (MZI) stage provides a first phase delay between the first and second feeds based on a first control signal, and a first mixer mixes the first and second feeds to provide third and fourth feeds. A second MZI stage provides a second phase delay between the third and fourth feeds based on a second control signal, and a second mixer mixes the third and fourth feeds to provide fifth and sixth feeds. A third MZI stage provides a third phase delay between the fifth and sixth feeds based on a third control signal, and a third mixer mixes the fifth and sixth feeds to provide the fixed target polarization. An optical tap splits a portion of the beam.

Abstract: An optical coupling apparatus for coupling an optical fiber to a photonic chip is described. The apparatus includes a collimating microlens for collimating light from the optical fiber; a polarization splitting beam displacer for separating the light collimated by the collimating microlens into orthogonally polarized X and Y component beams; at least one focusing microlens for directing the X and Y component beams separately onto the photonic chip; and first and second surface grating couplers (SGCs) orthogonally disposed on the photonic chip and configured for operation in a same polarization state, for coupling the X and Y component beams, respectively, to the photonic chip.

Abstract: An optical attenuator and/or optical terminator is provided. The device includes an optical channel having two regions with different optical properties, such as an undoped silicon region which is less optically absorptive and a doped silicon region which is more optically absorptive. Other materials may also be used. A facet at the interface between the two regions is oriented at a non-perpendicular angle relative to a longitudinal axis of the channel. The angle can be configured to mitigate back reflection. Multiple facets may be included between different pairs of regions. The device may further include curved and/or tapers to further facilitate attenuation and/or optical termination.