Coherent pulsed lidar system with two-sided detector

A lidar system comprising:

• a light source configured to emit (i) local-oscillator light and (ii) pulses of light;
• a receiver configured to detect the local-oscillator light and a received pulse of light, the received pulse of light comprising a portion of one of the emitted pulses of light scattered by a target located a distance from the lidar system, wherein the receiver comprises:
• a detector configured to produce a photocurrent signal corresponding to a coherent mixing of the local-oscillator light and the received pulse of light, wherein the detector comprises a first input side and a second input side located opposite the first input side, wherein 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, wherein the detector is a multi-element detector comprising a plurality of active regions distributed along a propagation axis of the local-oscillator light, wherein each active region is configured to produce at least a portion of the photocurrent signal, wherein the active regions comprise a first set of active regions and a second set of active regions, wherein the first and second sets of active regions are interleaved, wherein one active region of the second set is located between each pair of adjacent active regions of the first set, and wherein the photocurrent signal comprises a first portion and a second portion, wherein the first portion of the photocurrent signal is produced by the first set of active regions, and the second portion of the photocurrent signal is produced by the second set of active regions;
• and
• a pulse-detection circuit configured to determine, based at least in part on the photocurrent signal, a time-of-arrival for the received pulse of light;
• and
• a processor configured to determine the distance from the lidar system to the target based at least in part on the time-of-arrival for the received pulse of light.