Self-Sustained Generation of Dual-Chirp Microwave Waveforms

In this paper, we propose and demonstrate a dual-chirp microwave signal generator based on a dual-loop optoelectronic oscillator (OEO). A dual-parallel Mach-Zehnder modulator (DPMZM) is utilized in the OEO. The two sub-modulators of DPMZM are working at the minimum transmission point. One sub-modulator is driven by a baseband single-chirp signal, and another is by the feedback oscillating signal. In the experiments, dual-chirp microwave waveforms centered at 8GHz with a bandwidth of 1GHz and a period of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1}\boldsymbol{\mu}\mathbf{s}$</tex> are successfully generated and transmitted through a 40-km single-mode fiber. Moreover, dispersion-induced power fading is eliminated by adjusting the bias voltage of the main modulator.