High-Sensitivity Sensor in Localized Plasmonic Hybrid Resonator

Surface Plasmon Polaritons (SPP) are hybrid electromagnetic modes generated by the strong coupling of electromagnetic oscillations and electronic oscillations in metals. However, in the microwave and terahertz bands, due to the weakened skin effect of metals and the reduced effective electrical conductivity, they are difficult to be directly excited. Localized Spoof Surface Plasmonic (LSSP), as a functional material that achieves electromagnetic characteristics similar to SPP in this frequency band, has unique advantages such as deep wavelength compression and high sensitivity. This thesis focuses on the research of tunable LSSP devices. Based on the strong dispersion and high field restraint of LSSP, a microwave sensor with high sensitivity and high Figures of Merit (FOM) is designed. When the dielectric constant of the measured medium varies from 2 to 4, the dipole mode frequency shifts up to 270 MHz. With a sensitivity of 135 MHz/RIU, after introducing a crack, the FOM value of the dipole mode increased by approximately 4.4% while maintaining the sensitivity, and the excitation efficiency improved by 22%. The LSSP composite resonator, with its ultra-compact effective wavelength, low-cost manufacturing process and high Quality Factor (Q), has great application potential in microwave non-destructive testing fields such as micro-biomedicine and chemical sensing, achieving precise regulation of the electromagnetic characteristics of local artificial plasmons. 表面等离激元（Surface Plasmon Polaritons, SPP）是电磁振荡与金属中电子振荡强烈耦合产生的混合电磁模，但在微波和太赫兹波段，因金属趋肤效应减弱、有效电导率降低，难以直接激发。局域型人工表面等离激元（Localized Spoof Surface Plasmonic, LSSP）作为在此频段实现类似SPP电磁特性的功能材料，具备深度波长压缩、高灵敏度等独特优势。本论文围绕可调谐的LSSP器件展开研究，基于LSSP强色散和高场束缚性，设计出高灵敏度、高优值系数（Figures of Merit, FOM）的微波传感器，被测介质介电常数在2 - 4变化时，偶极模频移达270 MHz，灵敏度为135 MHz/RIU，引入裂纹后，在保持灵敏度的同时，偶极模FOM值提高约4.4%，激励效率提升22%。LSSP复合谐振器凭借超紧凑有效波长、低成本制造工艺和高品质因数（Quality Factor, Q），在微量生物医学和化学传感等微波无损检测领域极具应用潜力，实现了对局域型人工等离激元电磁特性的精确调控。