Silicon photonic phase interrogators for on-chip calibration of optical phased arrays

Correcting phase errors is key to building low cost, high performance integrated optical phased arrays for mass-market applications such as automotive lidar. In this work, we present a phase interrogator component for optical phased arrays which enables the phase error to be measured immediately before the output array of optical emitters. A 32-element silicon/silicon nitride optical phased array is realized in a dual layer photonics stack to verify the component performance. Silicon enables high density integration of photonic components and the phase interrogator has a compact design which fits between waveguides with a separation of 2.5 mu m. The phase interrogators enable correction of the beam without any measurement or evaluation of the far-field.