Abstract: In one embodiment, a lidar system includes a wavelength-tunable light source configured to emit pulses of light, each emitted pulse of light having a particular wavelength of multiple different wavelengths. The lidar system also includes a scanner configured to scan the emitted pulses of light across a field of regard of the lidar system. The scanner includes (i) a beam deflector configured to angularly deflect each emitted pulse of light along a first scan axis according to the particular wavelength of the emitted pulse of light and (ii) a scan mirror configured to scan the emitted pulses of light along a second scan axis different from the first scan axis. The lidar system further includes a receiver configured to detect a received pulse of light that includes a portion of one of the emitted pulses of light scattered by a target located a distance from the lidar system.

Abstract: Amplifier input protection circuits are described. In one embodiment, a photoreceiver for a lidar system has a photodetector configured to generate an output current in response to received light. A transimpedance amplifier is configured to receive the output current and generate a voltage output corresponding to the output current in response thereto, and a diode circuit has a cathode coupled at a node between the photodetector output and the transimpedance amplifier input.

Abstract: In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan the emitted pulses of light across a field of regard of the lidar system. The scanner includes (i) a beam deflector configured to direct each emitted pulse of light along a first scan axis and (ii) a scan mirror configured to scan the emitted pulses of light along a second scan axis different from the first scan axis. The lidar system also includes a receiver that includes a one-dimensional detector array that includes multiple detector elements arranged along a direction corresponding to the first scan axis. The receiver is configured to (i) detect a received pulse of light that includes a portion of one of the emitted pulses of light scattered by a target and (ii) determine a time of arrival of the received pulse of light.

Abstract: In one embodiment, a lidar system includes a light source configured to emit pulses of light, where each emitted pulse of light includes a spectral signature of multiple different spectral signatures. The lidar system also includes a receiver configured to detect a received pulse of light, the received pulse of light including light from one of the emitted pulses of light scattered by a target located a distance from the lidar system. The emitted pulse of light includes one of the spectral signatures. The receiver includes a detector configured to produce a photocurrent signal corresponding to the received pulse of light, a frequency-detection circuit configured to determine, based on the photocurrent signal, a spectral signature of the received pulse of light, and a pulse-detection circuit configured to determine, based on the photocurrent signal, a time-of-arrival of the received pulse of light.

Abstract: A system includes a light source, a receiver, and an enclosure. The light source is configured to emit an optical signal and the receiver is configured to detect a received optical signal including at least a portion of the emitted optical signal scattered by an external target. The enclosure includes a housing and a semiconductor window. The semiconductor window includes a semiconductor material configured to allow at least a portion of the emitted optical signal and the received optical signal to pass through the semiconductor window. The enclosure, including the housing and the semiconductor window, is configured to attenuate radio-frequency (RF) electromagnetic radiation.

Abstract: In one embodiment, a lidar system includes a light source configured to emit multiple optical signals directed into a field of regard of the lidar system. The optical signals include a first optical signal and a second optical signal, where the second optical signal is emitted a particular time interval after the first optical signal is emitted. The lidar system also includes a receiver configured to detect a received optical signal that includes a portion of the emitted first or second optical signal that is scattered by a target located a distance from the lidar system. The received optical signal is detected after the second optical signal is emitted. The receiver includes a first detector configured to detect a first portion of the received optical signal and a second detector configured to detect a second portion of the received optical signal.

Abstract: A receiver of a lidar system configured to receive one or more scattered light pulses from a target in a field of regard of the lidar system. The receiver includes a detector that emits an electric signal representative of the received light pulse in response to detecting the received light pulse. The receiver further includes one or more analog circuits configured to receive the electric signal from the detector, sample one or more voltages of the electric signal, and determine the energy of the received light pulse based at least on the one or more sampled voltages. The lidar system may further calculate a reflectivity and/or other characteristics of the target based at least on the energy of the received light pulse.

Abstract: In one embodiment, a lidar system includes a light source configured to emit (i) local-oscillator light and (ii) pulses of light. The lidar system also includes a receiver configured to detect the local-oscillator light and a received pulse of light, the received pulse of light including a portion of one of the emitted pulses of light scattered by a target located a distance from the lidar system. The receiver includes a detector configured to produce a photocurrent signal corresponding to a coherent mixing of the local-oscillator light and the received pulse of light. The detector includes a first input side and a second input side located opposite the first input side, where the received pulse of light is incident on the first input side of the detector, and the local-oscillator light is incident on the second input side of the detector.

Abstract: In one embodiment, a lidar system includes a multi junction light source configured to emit an optical signal. The multi junction light source includes a seed laser diode configured to produce a seed optical signal and a multi junction semiconductor optical amplifier (SOA) configured to amplify the seed optical signal to produce the emitted optical signal. The lidar system also includes a receiver configured to detect a portion of the emitted optical signal scattered by a target located a distance from the lidar system. The lidar system further includes a processor configured to determine the distance from the lidar system to the target based on a round-trip time for the portion of the scattered optical signal to travel from the lidar system to the target and back to the lidar system.

Abstract: A circuit for quenching an avalanche photodiode (APD) detector is disclosed herein. The circuit may comprise a discrete transistor configured to draw a quench current so as to enable a drop in a reverse bias voltage applied to the APD detector, and an integrated circuit connected to the discrete transistor, the integrated circuit including a plurality of circuit elements for controlling the reverse bias voltage.

Abstract: In one embodiment, a lidar system includes a light source configured to emit an optical signal and a receiver configured to detect an input optical signal that includes a portion of the emitted optical signal scattered by a target located a distance from the lidar system. The receiver includes an avalanche photodiode (APD) configured to receive the input optical signal and produce a photocurrent signal corresponding to the input optical signal. The APD includes a multiplication region that includes a digital-alloy region that includes two or more semiconductor alloy materials arranged in successive layers. The digital-alloy region is configured to produce at least a portion of the photocurrent signal by impact ionization. The receiver is configured to determine, based on the photocurrent signal produced by the APD, a round-trip time for the portion of the emitted optical signal to travel to the target and back to the lidar system.

Abstract: A lidar system includes a light source configured to emit light pulses and a receiver configured to detect light from some of the light pulses scattered by remote targets. The receiver includes an avalanche photodiode operating in the linear mode for detecting the light pulses. To prevent damage to the linear mode avalanche photodiode a quench circuit is coupled to the avalanche photodiode, where the quench circuit reduces a bias voltage applied to the avalanche photodiode, when an avalanche event occurs at the avalanche photodiode.

Abstract: Amplifier input protection circuits are described. In one embodiment, a photoreceiver for a lidar system has a photodetector configured to generate an output current in response to received light. A transimpedance amplifier is configured to receive the output current and generate a voltage output corresponding to the output current in response thereto, and a diode circuit has a cathode coupled at a node between the photodetector output and the transimpedance amplifier input.

Abstract: In one embodiment, a lidar system includes a light source configured to emit multiple optical signals directed into a field of regard of the lidar system. The optical signals include a first optical signal and a second optical signal, where the second optical signal is emitted a particular time interval after the first optical signal is emitted. The lidar system also includes a receiver configured to detect a received optical signal that includes a portion of the emitted first or second optical signal that is scattered by a target located a distance from the lidar system. The received optical signal is detected after the second optical signal is emitted. The receiver includes a first detector configured to detect a first portion of the received optical signal and a second detector configured to detect a second portion of the received optical signal.

Abstract: To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.

Abstract: In one embodiment, a lidar system includes a light source configured to emit pulses of light and a scanner configured to scan at least a portion of the emitted pulses of light across a field of regard. The lidar system also includes a receiver configured to detect at least a portion of the scanned pulses of light scattered by a target located a distance from the lidar system.

Abstract: A circuit for quenching an avalanche photodiode (APD) detector is disclosed herein. The circuit may comprise a discrete transistor configured to draw a quench current so as to enable a drop in a reverse bias voltage applied to the APD detector, and an integrated circuit connected to the discrete transistor, the integrated circuit including a plurality of circuit elements for controlling the reverse bias voltage.

Abstract: In one embodiment, a lidar system includes a light source configured to emit multiple optical signals directed into a field of regard of the lidar system. The optical signals include a first optical signal and a second optical signal, where the second optical signal is emitted a particular time interval after the first optical signal is emitted. The lidar system also includes a receiver configured to detect a received optical signal that includes a portion of the emitted first or second optical signal that is scattered by a target located a distance from the lidar system. The received optical signal is detected after the second optical signal is emitted. The receiver includes a first detector configured to detect a first portion of the received optical signal and a second detector configured to detect a second portion of the received optical signal.

Abstract: A scanning system includes a light source configured to emit light as a series of one or more light pulses, a scanner configured to direct the one or more light pulses towards a remote target, and a receiver configured to detect light scattered by the remote target. The receiver includes a light detector element disposed on an ASIC that includes multiple comparators disposed in parallel with one another, and corresponding time-to-digital converters (TDCs) coupled to the comparator. Each of the comparators processes a received electrical signal from the light detector element to produce a digital edge signal when the amplitude of the received electrical signal reaches a particular threshold. A corresponding TDC outputs a time delay value associated with a time at which the received electrical signal reaches the particular threshold.

Abstract: To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.