Photonic integrated circuit based compressive sensing radio frequency receiver using waveguide speckle

A photonic integrated circuit (PIC) comprised of an 11 cm long multimode speckle waveguide, a 1 × 32 splitter, and a linear grating coupler array is fabricated and utilized to receive 2 GHz of radio-frequency (RF) signal bandwidth from 2.5 to 4.5 GHz using compressive sensing (CS). Incoming RF signals are modulated onto chirped optical pulses which are input to the multimode waveguide. The multimode waveguide produces the random projections needed for CS via optical speckle. The time-varying phase and amplitude of two test RF signals between 2.5 and 4.5 GHz are successfully recovered using the standard penalized l1-norm method. The PIC reduces the speckle mixer footprint compared with the previously demonstrated fiber system. Two new PIC structures, the "waveguide bus trombone flare" and the "matched 90 degree bus bend" are developed to support precise analog signal routing. The use of a passive PIC serves as an initial critical step towards the miniaturization of a compressive sensing RF receiver.