Reconfigurable Generation of Switchable Multi-Format Linearly Frequency Modulated Signal at X-Band and K-Band With a Compact Photonics-Based Scheme

A photonic method for the reconfigurable generation of switchable multi-format linearly frequency modulated (LFM) signal using a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) is proposed and experimentally verified. By properly controlling the bias voltage applied on the DP-DPMZM, different chirp waveforms, including dual-chirped, down-chirped and up-chirped LFM signals, can be obtained when a radio frequency (RF) signal and a baseband chirped signal are injected into the modulator. Besides, the central frequency of the generated LFM signal can be converted from X-band to K-band by adopting -2(nd)-order sideband instead of -1(st)-order sideband of the modulated RF signal. Moreover, the RF signal is always single sideband modulated, thus eliminating the dispersion-induced power fading, which is essential for the photonics-based distributed multi-function radar. In the proposed scheme, no optical filter is required, which also improves the stability and feasibility of the system.