Effective Brillouin Gain Spectra Broadening for SBS Suppression Based on Pseudo Random Bit Sequence Phase Modulation in Fiber System

Binglin Li,Yifeng Yang,Yuqiao Xian,Meizhong Liu,Bing He,Jun Zhou

doi:10.1109/jphot.2021.3117659

Abstract

We describe stimulated Brillouin scattering process in a fiber system with light field phase modulated by lowpass filtered and amplified pseudo random bit sequence (PRBS) using localized nonfluctuating source model. The effective Brillouin gain spectra and the ratio of normalized Stimulated Brillouin Scattering (SBS) threshold to RMS optical linewidth is used to characterize the SBS suppression capability of the PRBS phase modulation. The normalized effective Brillouin gain spectra for different modulation parameters are calculated to exhibit the Brillouin gain broadening process. Based on the theoretical model, we find that the SBS threshold reaches a maximum for the ratio of cutoff frequency to clock rate <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rc = 0.53 and RMS modulation depth <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">krms = 0.55 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">π for PRBS9. An effective Brillouin gain spectrum measurement setup is established, and the theoretical predictions are verified by the experiment.

Highlights

STIMULATED Brillouin Scattering (SBS) is the lowest threshold nonlinear effect in narrow linewidth continuouswave fiber system [1]
We examine the effective Brillouin gain spectra broadening for filtered and amplified pseudo random bit sequence (PRBS) phase modulation in fiber system theoretically using localized nonfluctuating source model
The simulation indicated that for PRBS9, the effective Brillouin gain spectra will be broadened evenly and the SBS threshold reaches the maximum at krms=0.55 π, and rc=0.53

Summary

INTRODUCTION

STIMULATED Brillouin Scattering (SBS) is the lowest threshold nonlinear effect in narrow linewidth continuouswave fiber system [1]. The SBS process can be treated as a SBS amplifier when the Stokes wave is injected externally or seeded by the Rayleigh scattering near the output end of the medium. In this case, a simple model demonstrated by Zel’dovich can give an exactly analytical expression, which is so-called localized nonfluctuating source model [2]. We examine the effective Brillouin gain spectra broadening for filtered and amplified PRBS phase modulation in fiber system theoretically using localized nonfluctuating source model.

THEORETICAL FRAMEWORK

SIMULATION RESULT

EXPERIMENT SETUP

Findings

DISCUSSION

CONCLUSION