Photonic analog-to-digital conversion based on photonic time stretch and compressive sensing with optical random mixing

An approach to realizing photonic analog-to-digital conversion based on photonic time stretch and compressive sensing (CS) technique is proposed. A multi-tone signal (spectrally sparse) within a 20 GHz bandwidth is investigated. The wideband signal is firstly stretched in the time domain by a photonic time-stretcher and then reconstructed by CS based on random demodulator (RD). The random mixing in RD is realized optically with a spatial light modulator (SLM). Thanks to the techniques of time stretch and CS, wideband spectrally-sparse signals can be acquired effectively with a sampling rate far below the Nyquist rate. A system with time stretch factor 10 and compression factor 8, which means a 1/80 of the Nyquist rate, is illustrated.