Simulated Data for Comparison of On-chip Terahertz Filters for Sub-wavelength Dielectric Sensing

This paper discusses the application of on-chip terahertz (THz) filters attached to waveguides that can act as sensor elements, including for scanned imaging applications. Our work presents a comparative numerical study of several different geometries (comprising five split-ring resonator geometries and a quarter-wavelength stub resonator, the latter being well established as a sensor at THz frequencies and therefore able to act as a benchmark. We designed each structure to have a resonant frequency of 500 GHz, allowing the impact of resonator geometry on sensing performance to be isolated; the performance was quantified by assessing each design using four figures of merit: resonance quality factor, sensitivity (relative frequency shift under dielectric loading), responsivity (sensitivity weighted by resonance sharpness), and the electric field confinement area. Simulations were conducted using Ansys HFSS using the properties of commercially available photoresist (Shipley 1813) as a dielectric load to assess performance under conditions comparable to previous experimental studies. The analysis showed that while sensitivity remained broadly similar across geometries, responsivity and quality factor differed substantially between resonators. Furthermore, the spatial distribution of the electric field and current density, particularly in rotated configurations, was found to significantly impact coupling efficiency between the resonator and transmission line. Our findings provide guidance for the general design of systems employing THz sensors while establishing a framework with which to benchmark future sensor geometries.

本文探讨了集成于波导的片上太赫兹（terahertz, THz）滤波器作为传感单元的应用场景，涵盖扫描成像类应用。本研究针对多种不同几何结构开展对比数值分析，共包含5种开口环谐振器几何构型与1/4波长短截线谐振器；后者作为太赫兹频段已被广泛验证的传感结构，可作为性能基准参照。我们将所有结构的谐振频率统一设计为500 GHz，以隔离谐振器几何结构对传感性能的影响；通过四项性能指标量化评估各设计的表现：谐振品质因数、灵敏度（介质负载下的相对频移）、响应度（以谐振锐度加权的灵敏度）以及电场约束面积。仿真实验采用Ansys HFSS完成，并以商用光刻胶Shipley 1813的材料属性作为介质负载参数，以贴合此前实验研究的工况条件开展性能测试。分析结果表明，尽管不同几何构型的灵敏度整体相近，但各谐振器的响应度与品质因数存在显著差异。此外，研究发现电场与电流密度的空间分布（尤其是带旋转构型的结构）会对谐振器与传输线间的耦合效率产生显著影响。本研究成果可为太赫兹传感系统的通用设计提供参考依据，并构建了可用于基准测试未来传感几何结构性能的评估框架。