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研究了光纤激光器前向抽运的S波段分布式光纤拉曼放大器中级联的受激布里渊散射(SBS)串扰现象。用窄光谱带宽(<100MHz)的可调谐激光二极管作为信号源,通过S波段分布式光纤拉曼放大器,当被放大的信号功率超过单模光纤受激布里渊散射的阈值时,出现了前向受激布里渊散射,这是传导声波布里渊散射在光纤放大器中放大的现象。随着拉曼放大器抽运功率的提高,在斯托克斯区,出现了两阶受激布里渊散射线,在实验中观测到偶数阶的受激布里渊散射谱线功率大于奇数阶的布里渊一瑞利散射线。当进一步增加拉曼放大器的抽运功率,出现了前向级联的多阶受激布里渊散射现象,拉曼放大器的增益下降,被放大的信号功率转换为受激布里渊散射,噪声变大。受激布里渊散射的串扰破坏了拉曼放大器的特性,使拉曼放大器无法在密集波分复用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放大器的抽运功率。在实验中还观测到在光纤拉曼放大器中被放大的信号光和受激布里渊散射线两侧的伴线。
The cascaded stimulated Brillouin scattering (SBS) crosstalk phenomenon in the S-band distributed fiber Raman amplifier forward-pumped by fiber lasers was studied. With a tunable laser diode with a narrow spectral bandwidth (<100MHz) as the signal source, the S-band distributed fiber Raman amplifier appears when the amplified signal power exceeds the threshold for stimulated Brillouin scattering of single-mode fibers Stimulated Brillouin scattering, which is the phenomenon of conductive sonic Brillouin scattering amplified in a fiber amplifier. As the pumping power of the Raman amplifier increases, the second order stimulated Brillouin scattering appears in the Stokes region. It is observed experimentally that even order stimulated Brillouin scattering line power is greater than odd order The Brillouin-Rayleigh scattering. When the pumping power of the Raman amplifier is further increased, a forward cascade of multi-order stimulated Brillouin scattering occurs, the gain of the Raman amplifier decreases, the amplified signal power is converted to stimulated Brillouin scattering, the noise Bigger. Stimulated Brillouin scattering crosstalk undermines the characteristics of Raman amplifiers, so that Raman amplifiers can not be used in dense wavelength-division multiplexing optical fiber transmission systems, thus requiring strict control of the signal power into the fiber and the pump power of the amplifier. In the experiment, the amplitudes of signal and stimulated Brillouin scattered lines on both sides of the fiber Raman amplifier were also observed.