Photonic generation and transmission for an X-band dual-chirp waveform with frequency multiplication and power-fading compensation.

The generation of an X-band dual-chirp waveform, which is capable of pulse compression, plays an important role in radar, electric warfare, and satellite communication systems. With the development of applications such as multi-static radar, transmission over long distances has attracted considerable attention. In this paper, a photonic system for X-band dual-chirp waveform generation and transmission based on frequency multiplication and power-fading compensation is put forward and experimentally carried out. Based on a compact dual-parallel Mach-Zehnder modulator (DPMZM), the dual-chirp waveforms of 8.6-9.6 GHz and 9.6-10.6 GHz are generated by an RF carrier of 4.8 GHz and transmitted through a 40 km single-mode fiber (SMF) spool. The dispersion-induced power fading of the chirp waveform is compensated for by about 13 dB. The full width at half maximum (FWHM) and the peak-to-sidelobe ratio (PSR) of the compressed pulses are 1 ns and 11.5 dB, respectively. Moreover, the compensation of power fading in the entire X-band is verified to demonstrate the applicability of our system. By flexibly adjusting the bias voltage of the built-in phase shifter, the system can be applied in more scenarios.