Tunable Optoelectronic Oscillator Based on a Polarization Modulator and a Chirped FBG

A wideband-tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated based on a tunable microwave photonic filter (MPF) consisting of a polarization modulator, a chirped fiber Bragg grating, and a polarization beam splitter (PBS). By simply adjusting the polarization state of the signal before the PBS, the center frequency of the MPF is tuned. The proposed OEO is experimentally demonstrated. A high-purity microwave signal with a tunable frequency within 5.8–11.8 GHz is generated. The single-sideband phase noise of the generated signal is
${-}{\rm 104.56}~{\rm dBc}/{\rm Hz}$
at 10-kHz offset.