Nan Yinbo, Huo Li, Lou Caiyun
Department of Electronic Engineering, Tsinghua University, Beijing 100084, China.
Appl Opt. 2005 May 20;44(15):3045-50. doi: 10.1364/ao.44.003045.
We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions.
我们通过基于非线性薛定谔方程的数值模拟，对高非线性光纤中产生超连续谱（SC）连续波（cw）光源及其噪声特性进行了理论研究。泵浦脉冲的涨落会在纵向模式之间产生子结构，从而导致白噪声的产生，进而使相干性下降，调制深度和信噪比（SNR）降低。提出了一种基于超连续谱利用高非线性光纤（HNLF）、光学带通滤波器和法布里-珀罗（FP）滤波器相结合来提高多波长连续波光源信噪比的方案。数值模拟表明，调制深度的提高与高非线性光纤的长度、光学带通滤波器的3 dB带宽以及法布里-珀罗滤波器的反射率有关，在特定条件下调制深度的平均提高为13.7 dB。
