Brillouin Effect Impact in RoF Systems with Photonic-Assisted RF Amplification

Abstract

This work reports the impact of the stimulated Brillouin scattering (SBS) in a radio-over-fiber (RoF) system with photonic-assisted radiofrequency (RF) amplification. Such photonically amplified RoF systems employs long pieces of highly nonlinear fibers (HNLFs) for stimulating the four-wave mixing (FWM) nonlinear effect, in conjunction with appropriate management of the optical modulation index, aiming to provide RF gain. Numerical and experimental results demonstrate SBS might reduce the FWM nonlinear efficiency and limit the overall system power efficiency. We propose using only 35 m of HNLF for ensuring high photonic-assisted RF gain and increasing the SBS threshold in 14 dB. The digital performance of the photonically amplified RoF system is investigated in terms of root mean square error vector magnitude (EVMRMS), before and after mitigating SBS. The 35-m HNLF piece implies in enhancing the system digital performance and reducing in 6 dB the required optical power for attaining 19 dB of photonic-assisted RF gain.