Widely Tunable Optoelectronic Oscillator Using a Dispersion-Induced Single Bandpass MPF

A widely frequency tunable optoelectronic oscillator (OEO) based on a dispersion-induced single bandpass microwave photonic filter (MPF) is proposed and demonstrated. The MPF is implemented using a broadband optical source, a dual-output Mach–Zehnder modulator ( $1\times 2$ MZM) with unbalanced output fiber lengths into the upper and lower arms of the $1\times 2$ MZM, and a linearly chirped fiber Bragg grating. Through adjusting the difference between the two output fiber lengths after the $1\times 2$ MZM, the oscillation frequency of the OEO can be tuned by incorporating the MPF into an optical domain dual-loop OEO. A proof-of-concept experiment is performed. A microwave signal with a frequency tunable from 4.078 to 13.05 GHz is generated and its performance is investigated.