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设计了一种结构紧凑、工作频带较宽、耦合平稳、高方向性的“十字形”多孔耦合的太赫兹波导定向耦合器。基于多孔耦合原理,利用HFSS软件对太赫兹波导定向耦合器进行了模型仿真和结构优化。仿真结果表明:在325~475 GHz带宽范围内,该多孔耦合太赫兹波导定向耦合器耦合度达到7.5±0.8 d B,隔离度达到30 d B,即方向性优于20 d B,各端口回波损耗小于-20 d B。通过对该波导定向耦合器进行高温高压模拟仿真,确定了使用负性光刻胶SU-8作为结构材料的可行性,提出应用MEMS工艺在硅衬底上进行加工,将牺牲层工艺应用到波导腔结构的制作中。利用光刻在直通波导和耦合波导公共宽壁上形成的“十字形”等间距排列耦合孔结构,可以实现较宽的带宽和良好的耦合平坦度。该方法提高了耦合孔尺寸和位置的精度,减小了反射损耗,为太赫兹波导结构的加工提供了新思路。
A kind of terahertz-wave directional coupler with a compact structure, wide working band, smooth coupling and high directivity was designed. Based on the principle of porous coupling, model simulation and structure optimization of terahertz waveguided directional coupler were carried out by using HFSS software. The simulation results show that the coupling degree of the THz waveguide directional coupler reaches 7.5 ± 0.8 d B in the bandwidth of 325 ~ 475 GHz and the isolation degree reaches 30 d B, that is, the directivity is better than 20 d B, Wave loss less than -20 d B. Through the high-temperature and high-pressure simulation of the waveguide directional coupler, the feasibility of using negative photoresist SU-8 as the structural material is confirmed. The MEMS process is proposed to process the silicon substrate, and the sacrificial layer process is applied to the waveguide Cavity structure in the production. The use of lithography in the “cross” "equal spacing arrangement of the coupling hole structure formed on the common waveguide wall and the common waveguide waveguide wall, can achieve a wider bandwidth and good coupling flatness. The method improves the accuracy of the size and position of the coupling hole, reduces the reflection loss, and provides a new idea for the processing of the terahertz waveguide structure.