光纤布拉格光栅型全光纤声光调制器的特性研究

将光纤光栅的傅里叶模式耦合理论应用于光纤布拉格光栅型全光纤声光调制器的理论分析中. 与现有的分析方法相比, 该模型算法简单、 求解容易, 能够快速有效地获得调制器的传输特性. 基于该模型, 理论分析了超声波频率及声致应变幅度对调制器特性的影响. 仿真结果表明, 该调制器反射谱的主反射峰与次反射峰的波长间隔与超声波频率成正比, 反射峰的反射率随着声致应变幅度的改变而发生周期性的变化. 另外, 在同一声致应变幅度下, 低频超声波调制的光栅反射中存在更多的次反射, 光栅反射能量的周期性变化更加明显. 实验中, 使用频率为885.5 kHz的超声波对光纤布拉格光栅进行调制. 实验结果与仿真结果相一致.     

Investigation on the intensity noise characteristics of the semiconductor ring laser

Based on the frequency-domain multimode theoretical model, detailed investigations on the noise characteristic of the semiconductor ring laser （SRL） are first performed in this paper. The comprehensive nonlinear terms related to the third order nonlinear susceptibility Z3 are included in this model; the Langevin noise sources for electric field and carrier density fluctuations are also taken into account. As the injection current increases, the SRL may present several operation regimes. Remarkable and unusual low frequency noise enhancement in the form of a broad low frequency tail extending all the way to the relaxation oscillation peak is observed in any of the operation regimes of SRLs. The influences of the backscattering coefficient on the relative intensity noise （RIN） spectrum in typical operation regimes are investigated in detail.     

多偏振控制高双折射光纤环形镜输出特性的理论和实验研究

针对光纤环形镜(FLM)在单偏振控制下波长间隔不可调等缺点,对多偏振控制FLM的输出特性进行了理论和实验研究. 用Jones矩阵法分析了单偏振、双偏振和三偏振控制FLM的透射谱,研究发现: 相比单偏振控制FLM,多偏振控制FLM具有波长间隔可调和边频抑制等特性;透射谱的偏振可调性随偏振控制级数的增加而增强,实验结果与理论研究一致. 实验中利用双偏振控制FLM作为波长选择的光纤激光器输出激光的边模抑制比较采用单偏振控制FLM时提高了近5 dB. 关键词： 光纤光学 光纤环形镜 偏振控制 边频抑制