集成光学移相器波长相关性的比较研究

Comparison of wavelength dependence of integrated optical phase shifter

移相器是一种常用的集成光学结构,其相移值的波长相关性决定了移相器的工作波长范围。针对移相器的波长相关性,文中对两种集成光学移相器设计方案(长度差方案和折射率差方案)所设计的二氧化硅基集成光学移相器进行了实验研究。在马赫-曾德尔干涉仪(MZI)的两干涉臂之间,采用两种移相方案分别设计制作180°移相器,通过测试MZI的插入损耗与波长的依赖关系对两种移相器的波长相关性进行了比较。研究结果显示,折射率差方案所设计移相器的工作波长范围大约是长度差方案的1.8～1.9倍。这一实验结果与理论计算吻合,证明了折射率差方案设计的移相器的相移值波长相关性更小,因而具有更宽的工作波长范围。

Phase shifter is one of basic integrated optical structures, and wavelength dependence of its phase shift value determines operation wavelength range of devices. An experimental investigation was conducted on silica-based integrated optical phase shifter designed respectively in two different regimes,length difference regime(LDR) and refractive index difference regime(RIDR), aiming at wavelength dependence of phase shifter. Phase shifters of 180° were respectively designed in the two regimes and inserted between two interference arms of Mach-Zehnder interferometers(MZI). Based on these two structures, a quantitative comparison on phase shift wavelength dependence was made by measuring wavelength dependence of MZI insertion loss. Experimental results show that the operation wavelength range of phase shifters designed in the RIDR was approximately 1.8-1.9 times that designed in the LDR.Analysis shows that the experimental results are in agreement with the theoretical calculations, which proves that phase shifter designed in RIDR possesses weaker wavelength dependence and thus wider operation wavelength range.