Photonic Integrated Circuits for Angle-of-Arrival and Frequency Estimation

This paper demonstrates concurrent spatial and spectral signal classification using two photonic integrated circuits (PICs) implemented in a 30-element Ka-band (26.5-40 GHz) antenna array. The received signals are coherently up-converted to the optical-domain using lithium niobate phase modulators. The up-converted RF signal is beamformed in a star-coupler PIC to instantaneously image angle-of-arrival to a single output channel that is amplified and input to an arrayed waveguide grating (AWG) PIC, which instantaneously channelizes the RF frequency into increments of approximately 1 GHz. A switching scheme is used to calibrate the AWG as well as alternate between frequency and beam location measurement. This work implements these devices in a radiometer that can localize RF beams both spatially and spectrally with minimal latency and computational requirements. Future applications will include advanced wireless communications and sensing.