Wideband sparse signal acquisition with ultrahigh sampling compression ratio based on continuous-time photonic time stretch and photonic compressive sampling

In this paper, an approach to realizing wideband sparse signal acquisition with an ultrahigh sampling compression ratio based on continuous-time photonic time stretch (CT-PTS) and photonic compressive sampling (PCS) is proposed and experimentally demonstrated. In the system, a wideband sparse signal is slowed down in the time domain by a CT-PTS module and then down-sampled and reconstructed by a random-demodulator-based PCS scheme in which random mixing is realized with a pseudo-random binary sequence. Virtual time gating based on wavelength-to-time mapping and wavelength division multiplexing is used to realize CT-PTS to increase the length of the sampling window and finally improve the performance of PCS. In addition, single sideband modulation is employed to solve the problem of dispersion-induced power fading in PTS and therefore increase the bandwidth of the system. Due to the techniques of CT-PTS and PCS, wideband sparse signals can be acquired with sampling rates far below the Nyquist rate of the original signal. In the experiment, a sparse signal within 2–40 GHz bandwidth is successfully recovered with a sampling rate of 800 MS/s, which means a sampling compression ratio as high as 100.