Optical phased array with on-chip phase calibration

Abstract

Optical phased arrays (OPAs) with phase-monitoring and phase-control capabilities are necessary for robust and accurate beamforming applications. This paper demonstrates an on-chip integrated phase calibration system where compact phase interrogator structures and readout photodiodes are implemented within the OPA architecture. This enables phase-error correction for high-fidelity beam-steering with linear complexity calibration. A 32-channel OPA with 2.5-mu m pitch is fabricated in an Si-SiN photonic stack. The readout is done with silicon photon-assisted tunneling detectors (PATDs) for sub-bandgap light detection with no-process change. After the model-based calibration procedure, the beam emitted by the OPA exhibits a sidelobe suppression ratio (SLSR) of -11 dB and a beam divergence of 0.97 degrees x0.58 degrees at 1.55-mu m input wavelength. Wavelength-dependent calibration and tuning are also performed, allowing full 2D beam steering and arbitrary pattern generation with a lowcomplexity algorithm. (c) 2022 Optica Publishing Group