Detection of Low-Power RF Signals Using a Tunable Optoelectronic Oscillator

摘要

A tunable optoelectronic oscillator (OEO) for detecting low-power radiofrequency (RF) signals is proposed and experimentally demonstrated. The tunable OEO is mainly composed of a tunable laser source, a phase modulator, a phase-shifted fiber Bragg grating (PS-FBG) and a photodetector. The PS-FBG is used as a notch filter to remove one sideband of the phase-modulated signal to realize the phase modulation to intensity modulation conversion, which determines the main oscillation mode of the OEO. The frequency of the RF signal under detection can be estimated by the frequency difference between the optical carrier from the TLS and the notch of the PS-FBG. The RF signal as low as -75 dBm is detected with a dynamic range of 80 dB. The RF signals from 1.5 to 4.5 GHz are selectively amplified with a gain of about 7dB.