An Optoelectronic Oscillator Based on Carrier-Suppression-Effect-Free Single Bandpass Microwave Photonic Filter

A novel optoelectronic oscillator based on a single bandpass microwave photonic filter (MPF) without any electronic microwave filter is proposed and experimentally demonstrated. The MPF, which is composed by a broadband optical source, an inline interferometer based on a variable optical delay line (VODL), an intensity modulator, and a dispersive element, serves as an oscillating mode selector. The oscillation frequency can be tuned by changing the differential time delay via the VODL. Due to the non-carrier-suppression effect of the selector, the oscillator can generate transmission-null-free microwave signal with widely tunable frequency range. An experiment is performed, and a tunable frequency range of 6.8 GHz is achieved. The generated microwave signal at ~ 6.5 GHz ( ~ 1.06 GHz) exhibits a good phase noise performance about -95 dBc/Hz ( -110 dBc/Hz) at an offset of 10 kHz.