基于环形光纤的倾斜长周期光纤光栅的矢量模式转换  

Vector Mode Conversion Based on Tilted Long-Period Fiber Grating Written in Ring Fiber

作　　者：陶洪 芈月安 任文华[1,2] 简伟[1,2] 任国斌[1,2] Tao Hong;Mi Yuean;Ren Wenhua;Jian Wei;Ren Guobin(Key Laboratory of All Optical Network and Advanced Telecommunication Network of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China;Institute of Lightwave Technology,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学全光网络与现代通信网教育部重点实验室,北京100044 [2]北京交通大学光波技术研究所,北京100044

出　　处：《中国激光》2020年第6期237-243,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(61875008,61275092)。

摘　　要：为了实现模分复用系统中的模式转换,提出了基于环形光纤的倾斜长周期光纤光栅的矢量模式转换方法。利用有限差分法和耦合模理论,研究了折射率调制的倾斜角度、幅度函数、光栅长度及耦合系数对模式耦合的影响。结果表明,在相位匹配条件下,该光栅可在不同波长处实现基模到特定高阶矢量模式的转换,且波长间隔大于150 nm。倾斜角度在模式耦合中起着关键作用,在倾斜角度约为84°时转换效率可达到最大。与现有模式转换方法相比,这种模式转换器模式间隔较大,模式间串扰低、转换效率高,在轨道角动量复用和矢量模式复用中有潜在应用价值。In this study,we propose a vector mode conversion method based on tilted long-period fiber grating written in ring fiber to realize mode conversion with respect to the mode division multiplexing system.In addition,we study the influences of the grating parameters,including the tilt angle modulated based on the refractive index,the amplitude function,the grating length,and the coupling coefficient,on mode coupling using the finite difference method and the coupled-mode theory.The obtained results indicate that the fundamental mode can be converted to high-order vector modes at specific wavelengths under the phase-matching constraint;further,the wavelength interval is greater than 150 nm.The tilt angle plays a major role during the mode coupling process,and the maximum conversion efficiency can be obtained when the tilt angle is approximately 84°.The proposed converter has the advantages of larger mode interval,lower crosstalk,and higher conversion efficiency;therefore,it exhibits considerable potential for application in orbital angular momentum multiplexing and vector mode multiplexing when compared with those of the existing vector mode conversion methods.

关 键 词：光纤光学 倾斜长周期光纤光栅 矢量模式转换 少模环形光纤 耦合模理论 

分 类 号：TN253[电子电信—物理电子学]