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器件损耗偏高是当前聚合物电光调制器的研究中需要解决的问题之一。在调制器的插损之中 ,波导传播损耗 (包括吸收和散射损耗 )的贡献举足轻重。特别是在追求高电光系数的材料同时 ,传播损耗也将会不可避免地增加。如何改善器件的损耗是聚合物调制器实用化的一个重要课题。为此提出了一种在波导包层中调制光波的设想。理论分析表明 ,这种方法能够大幅度降低波导传播性能 ,因而有助于改善器件损耗。由于包层中光波强度比芯层中要弱 ,因此在包层中调制光波会引起场模交叠因子的弱化 ,但是优化计算发现 ,通过调节波导的尺寸尤其是芯层厚度可以控制交叠因子使其弱化程度降低到最小 ,在最优的情况下 ,场 -模交叠因子可达 0 .89。随着波导传播损耗的降低 ,器件调制区的长度可以做得更长 ,有助于进一步降低器件的半波电压。
High device loss is one of the problems to be solved in current polymer electro-optic modulator research. Among the modulator insertion losses, the contributions of waveguide propagation losses, including absorption and scattering losses, are of paramount importance. Especially in the pursuit of high electro-optic coefficient of material at the same time, transmission loss will inevitably increase. How to improve the loss of the device is one of the most important topics for practical application of polymer modulators. For this reason, a concept of modulating light wave in waveguide cladding is proposed. Theoretical analysis shows that this method can greatly reduce the waveguide propagation performance, thus contributing to improve the device loss. Because the intensity of the light in the cladding is weaker than that in the core, the modulation of the light in the cladding will cause the weakening of the field mode overlap factor. However, the optimization calculation shows that by adjusting the size of the waveguide, especially the thickness of the core, So that the degree of weakening is reduced to a minimum. Under optimal conditions, the field-mode overlap factor can reach 0 .89. With the reduction of waveguide propagation loss, the length of the device modulation region can be made longer, helping to further reduce the half-wave voltage of the device.