具有模式保持功能的片上模式分离器  

On-Chip Mode Splitter with Mode Maintenance Function

作　　者：廖莎莎 张伍浩 赵帅 赵薪程 唐亮 Liao Shasha;Zhang Wuhao;Zhao Shuai;Zhao Xincheng;Tang Liang(School of Communication and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆邮电大学通信与信息工程学院,重庆400065

出　　处：《光学学报》2024年第5期211-221,共11页Acta Optica Sinica

基　　金：重庆市教育委员会科学技术研究项目(KJQN202200613);国家自然科学基金区域创新发展联合基金(U22A2018)。

摘　　要：提出一种具有模式保持功能的片上模式分离器方案。该方案基于多模干涉耦合器(MMI),通过在MMI多模区加入微型热电极,并通过合理设计热电极的位置和精确控制热电极的加热温度,实现TE0、TE1和TE2三种模式的分离,其插入损耗均低于1.06 dB,模式串扰均低于-15.38 dB。该方案具有模式分离数量多和可扩展的优势,可被广泛用于信号处理系统和通信系统中。Objective The mode splitter is employed in mode division multiplexing systems to separate and guide different modes in a bus waveguide.Traditional mode splitter methods are based on mode conversion processes,where the input higher-order modes are converted into the fundamental mode to separate them from the bus waveguide.This method is suitable for most mode division multiplexing systems,but in scenarios such as signal routing or signal selection,when different modes are separated,they are often switched or selected using multi-mode switches.If the mode splitter output is all in the fundamental mode,additional components should be added after the mode splitter to convert the separated fundamental mode back to higher-order modes before inputting them into multi-mode switches,which undoubtedly increases the system complexity.In the case of optical isolation,it is often necessary to remove the higher-order modes and just transmit the fundamental mode.If the mode splitter output is all in the fundamental mode,it cannot meet the requirements of practical applications.Therefore,if the original modes can be preserved with mode separation achieved,this will greatly simplify the system structure and reduce the system size.Methods The multi-mode interference(MMI)coupler is a basic silicon-based device,that features a compact structure,low loss,and easy fabrication.However,traditional MMI-based mode splitters are difficult to extend the mode separation function to higher-order modes due to the highly symmetric structure and mode self-imaging principle.This scheme is based on the silicon-on-insulator(SOI)platform.According to the modal analysis method,it is derived that the refractive index distribution in the multi-mode region can not only change the imaging position and shorten the self-imaging length but also separate different input modes.Thermal tuning is achieved by fabricating heaters on top of the waveguide,and the waveguide material refractive index changes with the temperature at a rate of 1.84×10^(-4)K^(-1)due to

关 键 词：集成光学 模式保持 多模干涉耦合器 模式分离器 微型热电极 

分 类 号：TN256[电子电信—物理电子学]