An optically tunable frequency-doubling optoelectronic oscillator incorporating a phase-shifted-fiber-Bragg-grating-based frequency-tunable photonic microwave filter

A novel optically tunable frequency-doubling optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. A photonic microwave filter implemented using a phase modulator and a phase-shifted fiber Bragg grating (PS-FBG) is incorporated in the optoelectronic oscillator loop to ensure frequency-tunable single-frequency oscillation. A fixed optical filter is used at the output of the OEO loop to select one of the 2^nd-order sideband and the optical carrier. By beating the two wavelengths at a photodetector, a frequency-doubled microwave signal is generated. The microwave frequency can be continuously tunable by changing the wavelength of the optical carrier. An experiment is performed. The generation of a frequency-doubled microwave signal with a frequency tunable from 18 to 28 GHz is demonstrated. The phase noise performance of the generated microwave signal is also investigated.