Low-Loss Ultrawideband Programmable RF Photonic Phase Filter for Spread Spectrum Pulse Compression

We demonstrate a low-loss, ultrawideband (UWB), programmable radio frequency photonic phase filter utilizing a broadband optical frequency comb, interferometric pulse shaping configuration, and a balanced photodetector for spread spectrum pulse compression. We present UWB linear frequency-chirped pulse compression with bandwidths exceeding 7 GHz. The filter insertion loss for these experiments can be as low as 0.5 dB. In addition, the bandwidth and chirp rate of the phase filter are programmable. To further illustrate the programmability of the proposed filter, we report pulse compression experiments for UWB Costas sequences with bandwidth over 6 GHz. Finally, we perform a spread-spectrum jamming-resistant pulse compression experiment with the chirp filter, where a processing gain of ~ 17.3 dB, proportional to the time-bandwidth product of the filter, enables the recovery of a transmitted UWB signal in the presence of jamming.