非对称性对光子晶体光纤偏振相关滤波特性的影响

Effect of the Asymmetric Factor on the Polarization-dependent Filter of Photonic Crystal Fiber

基于表面等离子共振效应,提出了三种不同非对称因素引入的金镀膜偏振相关滤波光子晶体光纤,利用全矢量有限元法研究了光子晶体光纤偏振相关滤波传输特性.当非对称纤芯模单独作用时,波长1.55μm处x与y偏振方向纤芯模损耗分别为5.58dB/cm和461.58dB/cm,两偏振方向损耗比为83;当非对称金属表面等离子模单独作用,且镀膜厚度为55nm时,其谐振波长1.31μm处x与y偏振方向纤芯模损耗分别为2.02dB/cm和412.91dB/cm,两偏振方向损耗比高达204,镀膜厚度19.5nm时其谐振波长1.55μm处x与y偏振方向纤芯模损耗分别为5.29dB/cm和536.25dB/cm,两偏振方向损耗比为101;当纤芯模和表面等离子模同时引入非对称因素时,通信波长1.55μm处y偏振纤芯模谐振强度高达802.08dB/cm,而x偏振纤芯模损耗仅为5.57dB/cm,两偏振方向损耗比为144.数值比较可知,在金属表面等离子模中或两种模式同时引入非对称因素,可获得两偏振方向偏振损耗比更高的强偏振相关滤波传输特性的光子晶体光纤,该研究对光子晶体光纤偏振相关滤波器及相关偏振器件的设计与应用具有一定参考意义.

Based on the surface plasmon resonance effect,the gold-coated Photonic Crystal Fibers(PCFs)with introduction of three different kinds of asymmetric factors with polarization-dependent filter characteristics were proposed.The polarization-dependent filter characteristics were analyzed by the full vectorial finite element method.When the asymmetric factor is only introduced in the fiber core mode,the resonance losses of x-and y-polarized core modes are 5.58 dB/cm and 461.58 dB/cm at the communication wavelength of 1.55μm,respectively,the resonance loss ratio in two polarization directions is 83.When the asymmetric factor is only introduced in the surface plasmon mode,the resonance losses of x-and y-polarized core modes with the coating thickness of 55 nm are 2.02 dB/cm and 412.91 dB/cm at the resonance wavelength of 1.31μm,respectively,the resonance loss ratio in two polarization directions is up to 204.The resonance losses of x-and y-polarized core modes with the coating thickness of 19.5 nm are 5.29 dB/cm and 536.25 dB/cm at the resonance wavelength of 1.55μm,respectively,the resonance loss ratio in two polarization directions is 101.While the asymmetric factors both in the core modes and the surface plasmon mode are all introduced,the y-polarized resonance strength is up to 802.08 dB/cm at 1.55μm,the corresponding loss in x polarization is only 5.57 dB/cm,the resonance loss ratio in two polarization directions is up to 144.The numerical comparisons show that the asymmetric factors introduced in the surface plasmon mode or both in two modes can obtain much stronger polarization-dependent filter characteristics with high polarization loss ratio.This work is beneficial for the design and application of the polarization-dependent PCF filters and related polarizers.