Design, Fabrication, and Characterization of a Hybrid Integrated Photonic Module for a Synthetic Aperture Radar Receiver

Abstract

This paper presents the design, fabrication, and characterization of the first photonic-assisted receiver module for a Scan-on-Receive synthetic aperture radar (SCORE-SAR) intended for Earth observation from space. The module is a hybrid photonic integrated circuit (PIC) that is designed to do precise and continuous beamforming-on-receive of wideband signals from a 12 antenna elements array, synthesizing up to three simultaneous beams. The PIC also implements frequency-agnostic photonic down-conversion so that the synthesized beams can be directly digitized. The PIC is realized by the hybrid integration of active chips on indium phosphide and a passive chip on silicon nitride. The design steps of the photonic module are discussed in this paper, including: the functional designs, the optical mask designs, the filters designs, the printed circuit boards (PCB) design, and the control electronics that drive the PIC. Characterization and tuning of the different building blocks of the PIC is also presented, and frequency down-conversion functionality is experimentally demonstrated.