A wide-angle 1D optical phased array utilizing a passive phase-maintaining pitch-reduction structure

Integrated optical phased arrays (OPA) use on chip phase shifters to generate phase profiles across many integrated waveguides that are then coupled to a steerable free-space beam. A key metric to measure integrated OPAs is their field of view (FOV), which is the total angle that they can achieve coherent steering over. The pitch of the output elements often limits the FOV of an integrated OPA. In this work we describe the development and performance of a novel pitch-reduction structure that seeks to increase the FOV of a previously developed integrated OPA. We show an improvement of over 3X, increasing the FOV from 13.7° to 45.6°. These structures utilize silicon nitride as their waveguide material and thus are sufficiently phase stable across the 32 elements used in our arrays.