Ultrawideband RF compressed sensing using spectrally-encoded ultrafast laser pulses

We experimentally demonstrate a photonic RF sampling system that utilizes chirp processing of ultrafast laser pulses to achieve all-optical high-rate pseudorandom patterning and inner product integration for compressed sensing measurement. We successfully acquire multi-tone sparse radio frequency (RF) signals at arbitrary offsets from the reconstruction basis frequencies in an 11.95 GHz bandwidth utilizing less than 1% of the measurements traditionally required for Nyquist sampling. Pseudorandom binary sequence (PRBS) patterns are modulated onto time-stretched optical pulses, encoding them onto the optical spectra at a rate of one unique pattern per pulse. Thus patterned, the pulses are then partially-compressed, increasing the system´s effective sampling rate by 2.07×, well beyond the electronic modulation rate. The partially-compressed patterned pulses are then modulated again with the RF signal under test and fully compressed to perform optical integration of the PRBS-RF inner product before output photodetection and digitization. This achieves a reduction in required electronic sampling rate by two orders of magnitude.