Compensation of dispersion-induced power fading in radio-over-fiber system based on stimulated Brillouin scattering

Abstract

A method to compensate for the dispersion-induced power fading in a radio-over-fiber (RoF) link is proposed and experimentally demonstrated based on stimulated Brillouin scattering (SBS). In the central office, a part of the optical carrier is used to generate frequency-definable two-tone pump light via carrier-suppressed double-sideband modulation. The two-tone pump light generates both Brillouin loss and gain spectra at the vicinity of the optical carrier when it counter-propagates with the signal light in a spool of single-mode fiber (SMF) located in the central office. Hence, the relative phase difference between the optical carrier and the ±1st -order modulation sidebands of the signal light can be freely varied by using the SBS-induced carrier phase shift, which can compensate for the power fading induced by the group-velocity dispersion in the transmission fiber between the central office and the base station. In the experiment, a flat gain in the frequency range of 10 MHz to 10 GHz is achieved for the signal transmission over 45-km SMF. The error vector magnitudes (EVMs) of the transmitted 64 QAM signals centered at 4.8 GHz and 5.0 GHz are greatly improved after dispersion-induced power fading compensation.