Systems and methods for isolating excitation and signal paths for chip-scale LIDAR

Embodiments described herein improve the performance of active sensing systems, such as LiDAR systems, and enable detection of objects closer to the system's sensor. Illustrative embodiments enable spatial separation of the excitation and return signal on a photonic integrated chip ("PIC") such that separate waveguides can be used for the excitation and return signals, enabling isolation of the system's detectors from the excitation source without the use of a splitter or circulator. For example, preferred embodiments avoid loss due to the use of splitters and the need for gating the detector, and are desirably compatible with chip-scale systems. Moreover, illustrative embodiments enable keeping the excitation and detection paths on the same PIC (e.g. in an interleaved configuration), which helps keep the system more compact and avoid issues introduced by parallax.