On-Chip Pseudo-Random Microwave Waveform Generation Based on Random-Sampled Subwavelength Grating Waveguide Bragg Grating

We propose and experimentally demonstrate an integrated photonic approach for generating broadband pseudo-random microwave waveforms using random-sampled subwavelength grating waveguide Bragg gratings (RS SWG WBGs) implemented on a silicon-on-insulator (SOI) platform. Introducing randomness in the sampling structure results randomness in the reflection spectra, which shape a temporally stretched femtosecond light pulse through wavelength-to-time (WTT) mapping using dispersion compensating fiber (DCF). Experiments show a pseudo-random electrical waveform with a temporal duration of 5.12 ns and a bandwidth of 50.85 GHz, yielding a time-bandwidth product (TBWP) of 260. The pseudo-random waveform can be compressed from 5.12 ns to 19.6 ps, corresponding to a pulse compression ratio (PCR) of 261, in good agreement with the TBWP.