Dual-Loop Dual-Modulation Optoelectronic Oscillators With Highly Suppressed Spurious Tones

We successfully demonstrate an optoelectronic oscillator (OEO) low radio-frequency(RF)-threshold gain and a low level of spurious tones using semiconductor lasers under optical injection in dual fiber-loop configuration. Our 15-GHz OEO exhibits spurious tones suppressed over 70 dB by dual-loop modulation, maintaining a low RF-threshold gain of 27 dB and phase noise of 104 dBc/Hz at 10-kHz frequency offset.