带输入、输出端口的双芯光纤偏振分束器研究

Research of Twin-Core Optical Fiber Polarization Beam Splitter with Input and Output Waveguides

双芯光纤偏振分束器是一类基于模式干涉的偏振分束器,是以双芯光纤作为定向耦合器,经过双芯光纤的耦合区域后实现的偏振选择性输出,因而其输入、输出端的形状和尺寸会影响光的输出功率及特性。基于椭圆双芯光纤,在分束器的输出消光比满足一定要求(大于20dB)的情况下,借助于RSOFT软件的Beamprop模块,研究双芯光纤偏振分束器输入、输出端口的形状和尺寸以及输入光的波长和线偏振角度对偏振选择特性的影响,及其可能的工作带宽和制作容差。结果表明,双芯光纤偏振分束器形状为S-Bend,X和Z方向的尺寸分别为40μm和4000μm的端口,输入光的工作带宽可以大于7.5nm,对应的耦合区长度较短,约为209.87mm。

Based on modes interference, twin-core optical fiber polarization beam splitter can spatially separate different polarized incident lights according to the coupling length difference of the two orthogonal polarization states. Making the dual-core optical fiber as a directional coupler, the power and polarization selectivity of the twin-core optical fiber polarization beam splitter are affected by the shape and size of the input and output waveguides when the light goes through the twin-core coupling area. Based on an elliptical twin-core optical fiber beam splitter and the RSOFT-Beamprop numerical calculation, the effects of the shape and size on the polarization selectivity, the bandwidth and fabrication tolerance are researched under the required extinction ratio （≥20 dB）. The results show that the shape of twin-core optical fiber beam splitter is S-Bend, the input and output waveguide size is 40 μm and 4000 μm in the transversal X and longitudinal Z direction, respectively. Bandwidth of input light can greater than 7.5 nm and its coupled length is as comparatively short as about 209.87 mm.