光纤拉曼放大器中级联的前向受激布里渊散射

研究了前向抽运和背向抽运方式下S波段分布式光纤拉曼放大器(FRA)中级联的受激布里渊散射(SBS)现象。用窄光谱带宽(<100MHz)的可调谐LD作为信号源,通过S波段分布式FRA,当被放大的信号功率超过单模光纤SBS的阈值时,出现了前向SBS。随着FRA抽运功率的提高,在斯托克斯区,出现了级联的SBS线,信号的功率转换为SBS功率,在实验中观测到偶数阶的SBS谱线功率大于奇数阶的Brillouin Rayleigh散射线。当进一步增加FRA的抽运功率,其增益下,噪声变大,SBS的串扰破坏了FRA特性,使其无法在密集波分复用(DWDM)光纤传输系统中使用,因此需要严格地控制入纤的信号功率和FRA抽运功率。在实验中还观测到在FRA中被放大的信号光和SBS线两侧的伴线。

Cascaded Brillouin Scattering in a Distributed Fiber Raman Amplifier

The cascaded stimulated Brillouin scattering(SBS) on S-band forward pumped and backward pumped distributed fiber Raman amplifier(FRA) was studied.Forward SBS is observed during pump power is larger than the threshold value of SBS in a S-band FRA and signal source is a tunable narrow spectral bandwidth (<100 MHz) LD.Cascaded multi-order SBS is observed in the Stokes region during the pump power increases.The power of even order SBS is stronger than odd order Brillouin-Rayleigh scatterng in the experiment.The gain is down and noise increases during the pump power continuesly increases.FRA can not be used on DWDM transmit system because of the crosstalk of cascade SBS.So we must control pump power on FRA and incident signal power in fiber.Companion lines on two sides of amplified signal light and SBS is observed on S-band FRA.