Low-Power RF Signal Detection with High Gain Using a Tunable Optoelectronic Oscillator

A novel photonic method for low-power RF signal detection by a tunable optoelectronic oscillator (OEO) based on a dual-parallel Mach-Zehnder modulator (DP-MZM) and a phase-shifted fiber Bragg grating (PS-FBG) is proposed and experimentally demonstrated. The DP-MZM is utilized to generate the equivalent phase modulation (EPM) signal with partial optical carrier suppression. The EPM is helpful to enhance the gain to the RF signal in the OEO loop. The RF signals from 2 to 18 GHz as low as -87 dBm are detected with a gain of about 10 dB. Compared to normal phase modulation based scheme, the EPM-based system offers 9.1 dB higher gain.