Optoelectronic oscillator using push-pull Mach-Zehnder modulator biased at null point for optical two-tone signal generation

We propose a novel optoelectronic oscillator (OHO) made of a push-pull Mach-Zehnder modulator biased at null point, oscillating at half the frequency of feedback signal. Optical two-tone signal with 10.5-GHz frequency difference is experimentally generated.