基于非线性放大环镜的全光开关特性研究

采用掺铒光纤放大器(EDFA)和高非线性色散位移光纤(HNL—DSF)组成非线性放大环镜(NALM)，利用掺铒光纤放大器的高增益系数和高非线性色散位移光纤的光学克尔效应构造全光开关，实现脉冲整形和消除干扰噪声。采用分布傅里叶法分析了高非线性色散位移光纤的群速度色散(GVD)对非线性放大环镜开关特性的影响，讨论了掺铒光纤放大器的增益系数、增益饱和特性以及耦合器的耦合比等因素的影响，研究了入射光为高斯脉冲的情况下，非线性放大环镜与入射光信号强度相关的放大滤波特性。通过优化非线性放大环镜的各项参数，可以在实现高开关效率的同时，降低对开关功率的要求，对峰值功率低于1mW的超短脉冲进行Tbit／s量级的开关操作，从而适用于超高速大容量光通信系统中。

Analysis of the Characteristics of the All-Optical Switch Based on Nonlinear Amplifying Loop Mirror

A kind of all-optical switch, which is constructed by a nonlinear amplifying loop mirror (NALM) based on erbium-doped fiber amplifier (EDFA) and high nonlinear dispersion shifted fiber (HNL-DSF), is presented. With the high gain coefficient of EDFA and the optical Kerr effect of HNL-DSF, this configuration can be used to shape the optical pulse and suppress the pedestal and noise. The effect of group velocity dispersion (GVD) of HNL-DSF on the switch characteristics of NALM is analyzed by split-step Fourier method. Meanwhile, the effects of the gain coefficient, the saturation of EDFA and the coupling ratio of optical coupler are discussed theoretically and numerically. NALM has intensity-dependent filtering character and the input power required to obtain nonlinear input-output relationship reduces to a low level. Through optimizing every parameter, a switching operation over 1 Tbit/s can be realized on the short pulse and the threshold value of the switch can be lower than 1 mW.