为提高波分复用(WDM)光通信网中核心器件光开关的响应速度,设计并制备了SiO2/聚合物复合型Y分支结构波导热光开关。器件选择具有高热导率的SiO2作为波导的下包层,低成本的聚甲基丙烯酸甲脂一甲基丙烯酸环氧丙酯共聚物(P(MMA—GMA))作为芯层和上包层,利用束传播法模拟和优化Y分支波导的设计,通过光刻、刻蚀和蒸发等传统半导体工艺进行器件制备。实验测得开关插入损耗为12dB,消光比为18dB,方波驱动的上升和下降响应时问均为200μs。实验结果表明,SiO2/聚合物复合波导结构可有效提高热场的扩散速度和折射率调节效率,减小开关的响应时间。
To improve the response speed of optical switches in the optical communication networks, a SlOe/polymer hybrid waveguide structure is used in the design and fabrication of the Y branch thermooptical switch. The silica with large thermal conductivity is adopted as the lower cladding of the waveguide. The low cost polymer of poly(methyl methacylate-glyciclyl methacrylate) with favorable op- tical properties is adopted as the core and upper cladding material. The optical field propagation is simu- lated by beam propagation method (BPM). According to optical mode calculations by Matlab, the width and height of this hybrid waveguide are optimized to be 3, 5μm. Through methods of spin-coating,pho- tolithography and inductively coupled plasma etching, the switch waveguide is fabricated. Characterization by scanning electron microscope (SEM) shows that the polymer waveguide has a vertical sidewall and square configuration, which is favorable for the confinement of optical mode and the reduction of optical loss. The experimental results indicate that the optical insert loss and extinction ratio of the fabricated switch are 12 dB and 18 dB,respectively. Since hybrid waveguide structure can improve the diffusion of the thermal field in the waveguide and reduce the response time effectively,the rise time an fall time are only 200μs. This switching speed is faster than that of thermo-optic switches adopting polymer as the lower cladding.