中国激光, 2016, 43 (9): 0906002, 网络出版: 2018-05-25
单偏振双芯光子带隙光纤定向耦合器
Single-Polarization Directional Coupler Based on Dual-Core Photonic Bandgap Fiber
光纤光学 光子带隙光纤 单偏振定向耦合器 谐振式光纤陀螺 热致偏振串扰 fiber optics photonic bandgap fiber single-polarization directional coupler resonant fiber optic gyro thermally induced polarization crosstalk
摘要
提出了一种基于双芯光子带隙光纤(PBF)的单偏振(SP)定向耦合器,利用全矢量有限元方法(FEM)对其耦合特性进行了研究。结果表明:通过适当调整纤芯间微孔的大小及掺杂折射率可在耦合器获得SP特性;而纤芯间微孔椭圆率的变化并不会对其SP特性造成干扰,耦合器具有较高的结构参数容错性;通过优化参数,最终获得了一种长度仅为0.403 mm的SP定向耦合器。该耦合器在全保偏PBF(PM-PBF)谐振腔应用中, 能同时起到分束器及起偏器的作用,可以破坏次本征偏振态(ESOP)的谐振条件,有效抑制次ESOP的传输。这种具有较短长度的SP定向耦合器模场可与之前提出的PM-PBF的模场相匹配,有利于搭建起全PM-PBF谐振腔,这对抑制谐振式光纤陀螺(RFOG)热致偏振串扰噪声、提高RFOG的长期稳定性具有重要意义。
Abstract
A single-polarization (SP) directional coupler based on dual-core photonic bandgap fiber (PBF) is proposed, and the coupling properties of the coupler are studied numerically using the full vector finite element method (FEM). Results show that by appropriately adjusting the size of the holes between the cores and the refractive index of doping, the SP property can be obtained in a coupler; however, the ellipticity of the hole between two cores has no effect on the SP property, which means that the coupler has high structure parameter error tolerance; an SP directional coupler with length of 0.403 mm is obtained by optimizing the parameters. In the application of the all polarization-maintaining PBF (PM-PBF) based resonant cavities, the coupler can serve as a beam splitter and a polarizer at the same time, break the resonant condition of secondary eigenstate of polarization (ESOP) and effectively inhibit its transmission. The mode field of SP coupler with short length matches with the PM-PBF proposed in former study, which is beneficial to the establishment of an all PM-PBF resonant cavities, and therefore has great significance in reducing the thermally induced polarization crosstalk noise of resonator fiber-optic gyroscopes (RFOG) and improving the long-term stability of RFOG.
李绪友, 许振龙, 凌卫伟, 刘攀, 夏琳琳, 杨汉瑞. 单偏振双芯光子带隙光纤定向耦合器[J]. 中国激光, 2016, 43(9): 0906002. Li Xuyou, Xu Zhenlong, Ling Weiwei, Liu Pan, Xia Linlin, Yang Hanrui. Single-Polarization Directional Coupler Based on Dual-Core Photonic Bandgap Fiber[J]. Chinese Journal of Lasers, 2016, 43(9): 0906002.