基于LCOS的可调谐光学滤波器的研究与设计

发布时间：2018-11-24 14:46

【摘要】：新一代全光网络要求其ROADM(Reconfigurable Optical Add/Drop Multiplexer,可重构光分插复用器)节点能够进行波长粒度的光交换,带通型可调谐光学滤波器(Tunable Optical Filter,TOF)和波长选择开关(Wavelength Selective Switch,WSS)在这种新型ROADM节点中有着重要的应用。本文研究基于LCOS(Liquid Crystal on Silicon,硅基液晶)技术的可调谐光学滤波器,主要研究工作如下:研究了液晶的电光效应和LCOS的相位调制原理,讨论了基于LCOS的光束偏转技术原理,基于位相差分析方法初步得到:LCOS动态相位光栅的衍射特性取决于单像素衍射、闪耀光栅干涉和阶梯光栅干涉三个因子,衍射光能量集中于+1级衍射光,可以获得较高的衍射效率,LCOS对入射光束的偏转角度即为+1级衍射光的衍射角。设计了一种自由空间光学结构的带通型可调谐光学滤波器阵列(Tunable Filter Array,TFA),通过LCOS芯片上的像素分割和光束偏转实现TFA通带的选择。对TFA模块中的高斯光束参数匹配、LCOS芯片像素分割等问题进行了深入的分析,在此基础上,对色散系统、扩束元件、偏振转换组件、光纤阵列、微透镜阵列等光学组件进行了详细的参数设计,并对整体光学系统进行了软件仿真。WSS可视为一种1×K端口的带通型TOF,考虑LCOS在WSS模块中的实际应用情况,建立了简化的2f光学系统模型,基于高斯光学和傅里叶光学理论,分析了LCOS动态相位光栅的衍射特性与WSS模块的性能指标之间的关系。得到结论:LCOS芯片中的电场边缘效应对WSS模块的串扰指标影响最大,为满足串扰-30dB,应保证光栅周期Λ23.75,此要求限制了WSS的端口数。相关研究成果对WSS模块的优化设计有重要的参考价值。
[Abstract]:A new generation of all-optical network requires that its ROADM (Reconfigurable Optical Add/Drop Multiplexer, reconfigurable optical add / drop multiplexer node can perform wavelength granularity optical switching, band-pass tunable optical filter (Tunable Optical Filter,TOF) and wavelength selective switch (Wavelength Selective Switch, WSS) has important applications in this new ROADM node. The tunable optical filter based on LCOS (Liquid Crystal on Silicon, silicon based liquid crystal technology is studied in this paper. The main work is as follows: the electro-optic effect of liquid crystal and the principle of phase modulation of LCOS are studied, and the principle of beam deflection based on LCOS is discussed. Based on the phase analysis method, it is preliminarily concluded that the diffraction characteristics of the LCOS dynamic phase grating are determined by three factors: single pixel diffraction, blazed grating interference and step grating interference, and the diffraction energy is concentrated in the first order diffraction light. A higher diffraction efficiency can be obtained, and the deflection angle of LCOS to the incident beam is the diffraction angle of the first order diffraction light. A band-pass tunable optical filter array (Tunable Filter Array,TFA) with free-space optical structure is designed. The selection of TFA passband is realized by pixel segmentation and beam deflection on LCOS chip. Based on the analysis of Gao Si beam parameter matching and LCOS chip pixel segmentation in TFA module, the dispersion system, beam expander, polarization conversion module, fiber array, and so on are analyzed. The optical components such as microlens array are designed in detail, and the whole optical system is simulated by software. WSS can be regarded as a band-pass TOF, with 1 脳 K port considering the practical application of LCOS in WSS module. A simplified 2f optical system model is established. Based on Gao Si optics and Fourier optics theory, the relationship between the diffraction characteristics of LCOS dynamic phase grating and the performance index of WSS module is analyzed. It is concluded that the electric field edge effect in LCOS chip has the greatest influence on the crosstalk index of WSS module. In order to satisfy the crosstalk -30dB, the grating period A 23.75 should be guaranteed, which limits the number of WSS ports. The related research results have important reference value for the optimization design of WSS module.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713;TN929.1

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