【作者】 张云；

【导师】 张德龙；

【作者基本信息】 天津大学 ， 光学工程， 2004， 硕士

【摘要】 本文比较详细地论述了长周期平板波导光栅的基本理论,其中包括平板波导理论、模式耦合理论、波导光栅理论、微扰论以及波导系统的传输线理论,并在此基础上推导出长周期波导光栅的模式耦合方程和位相匹配条件。为了比较不同波导材料对长周期波导光栅的影响,我们以折射率不同的两种聚合物材料BCB(Bis-Benzo-Cyclobutene,1550nm时折射率为1.54224)或者ENR(Epoxy-novolak-resin,1550nm时折射率为1.57)为光栅和波导的核心材料,以PMMA(Polymethyl-methacrylate)为覆盖层,以二氧化硅为基底层的长周期波导光栅为例,较系统的阐述了长周期波导光栅的波导的设计原理,并详细讨论了波导光栅的设计参数对传输光谱的影响,从而对长周期波导光栅在掺铒光纤放大器增益平坦化以及滤波方面的应用作了简单地分析探讨。文中分TE模和TM模两种情况,利用C程序和MATLAB语言编制相关程序,计算出了波导光栅中传输光波的单模条件,绘制了导模层厚度与光栅周期的关系曲线以及长周期波导光栅的周期与波导透射功率谱中最大功率衰减位置的关系曲线,即位相匹配曲线等。分析的参数涉及波导光栅的周期、波导层厚度对传播模式的影响、光栅的高度和光栅长度对最大功率衰减峰以及3dB带宽等的影响。此外,还对可能出现的双共振波长和过耦合现象进行了分析和论述。更多还原

【Abstract】 The relevant theories for long-period waveguide grating (LPWG) are demonstrated that include planar wavguide theory, coupled-mode theory, waveguide grating theory, perturbation analysis and transmission line method. On the basis of these theories, the coupled-mode equation and phase-matching condition suitable for LPWG are derived.To demonstrate the effect of different materials on the LPWG, two kind of polymers: Bis-benzo-cyclobutene (BCB) and Epoxy-novolak-resin (ENR) are selected as both guiding layer and grating materials, with the polymethyl-methacrylate (PMMA) as the cladding material and with the silicon dioxide on silicon (SiO2/Si) as the substrate. The principle of designing an optimized LPWG is demonstrated in detail and the effect of the LPWG parameters on the power transmission spectrum is also described from the role of the application of LPWG as a gain flattening device for erbium-doped filter amplifier (EDFA).Our results cover both TE and TM modes. Using C program and MATLAB language, single mode condition of LPWG with two kinds of key materials is obtained. The dependence of grating period on the waveguide layer thickness and the dependence of the maximum attenuation (dip) on the grating period in transmission spectrum i. e. the so-called phase-matching curve, were calculated. The effect of the grating period, the waveguide thickness, the grating height and length on the dip and FWHM are discussed. In addition, the dual-resonance and over-coupling phenomenon are also explained.更多还原