Photonic approach for the generation of switchable down-, up-, and dual-chirped linear frequency-modulated microwave signals.

A photonic approach to generate switchable down-, up-, and dual-chirped linear frequency-modulated (LFM) microwave signals utilizing a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. By properly controlling the radio frequency signals and baseband LFM signals applied to the DP-DPMZM, switchable down-, up-, and dual-chirped LFM microwave signals with a tunable center frequency and chirp rate can be obtained. Experimental results show that switchable down-, up-, and dual-chirped LFM signals with a center frequency of 5 GHz and chirp rate of 1 GHz/4 µs are generated. In addition, the tunability of the center frequency and chirp rate of the generated microwave signals are also demonstrated.