基于宽带非相干抽运光源的慢光延迟理论研究

从理论上分析了基于谱分割宽带非相干放大自发辐射(ASE)光源作为抽运信号产生受激布里渊散射(SBS)效应实现慢光延迟的特性。着重考虑了慢光效应对传输系统性能的影响, 对2.5 Gbit/s的非归零(NRZ)和归零(RZ)伪随机码进行了数值分析, 得到了延迟信号眼图、延迟量及Q因子在不同谱分割带宽和功率下的变化趋势。结果表明, 增大抽运功率和减小谱分割带宽有利于增加信号的延迟, 但延迟信号的扰动加大, 因而Q因子减小, 恰当选取抽运功率和谱分割带宽可以在保证延迟量的情况下提高Q因子, 有助于系统性能的优化。与传统实现宽带抽运脉冲方法相比, 使非相干ASE光源通过一个光纤布拉格光栅(FBG)滤波器, 可以很方便地得到吉赫兹带宽的抽运脉冲, 因而大大降低了系统的复杂度及成本, 且延迟量可以和传统方法相比拟。

Theoretical Study on Slow-Light Delays Using Broadband Incoherent Pumping Source

We theoretically analyze characteristics of stimulated Brillouin scattering (SBS)-based slow light using a broadband incoherent and spectrally-sliced ASE source as the pump. Different from most previous literatures where only the delay characteristics of a single pulse are investigated, we concentrate on the transmission system performance when the slow light delay is incorporated. Under different spectrally sliced bandwidths and pump power levels, the output eye diagrams, the trends of the delay time and the Q factor are obtained through numerical analysis for both nonreturn-to-zero(NRZ) and return-to-zero(RZ) data formats modulated by 2.5-Gbit/s pseudo-random bit sequences. The results show that increasing the pump power and reducing the spectrally-sliced bandwidth are both beneficial to the generated delay, while the Q-factor may degrade due to more serious signal perturbation. By properly choosing the pump power and the spectrally-sliced bandwidth, we may optimize the Q-factor without sacrificing the delay time. Using a fiber Bragg grating (FBG) as the filter after the ASE source, we can easily obtain the pumping source with～GHz bandwidth therefore greatly reduce the system complexity and the cost, with the generated delay still comparable to conventional approaches.