Advances in mid-IR lasers, detectors, and nanofabrication technology have enabled new device architectures to implement on-chip sensing applications. In particular, direct integration of plasmonic resonators with a dielectric waveguide can generate an ultra-compact device architecture for biochemical sensing via surface-enhanced infrared absorption (SEIRA) spectroscopy. A theoretical investigation of such a hybrid architecture is imperative for its optimization. In this work, we investigate the coupling mechanism between a plasmonic resonator array and a waveguide using temporal coupled-mode theory and numerical simulation. The results conclude that the waveguide transmission extinction ratio reaches maxima when the resonator-waveguide coupling rate is maximal. Moreover, after introducing a model analyte in the form of an oscillator coupled with the plasmonics-waveguide system, the transmission curve with analyte absorption can be fitted successfully. We conclude that the extracted sensing signal can be maximized when analyte absorption frequency is the same as the transmission minima, which is different from the plasmonic resonance frequency. This conclusion is in contrast to the dielectric resonator scenario and provides an important guideline for design optimization and sensitivity improvement of future devices.

中文翻译：

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与硅波导集成的等离子体共振器的耦合模式理论，适用于中红外光谱感测。

中红外激光器，检测器和纳米加工技术的进步使新的器件架构能够实现片上传感应用。特别是，等离振子谐振器与介电波导的直接集成可以通过表面增强红外吸收（SEIRA）光谱生成用于生物化学传感的超紧凑型设备架构。对这种混合体系结构进行理论研究是其优化所必需的。在这项工作中，我们使用时间耦合模式理论和数值模拟研究等离子体激元谐振器阵列和波导之间的耦合机制。结果表明，当谐振器与波导的耦合速率最大时，波导的消光比达到最大值。此外，在以振荡器形式与等离子波导管系统耦合引入模型分析物之后，可以成功拟合具有分析物吸收的传输曲线。我们得出的结论是，当分析物的吸收频率与透射最小值相同（不同于等离子体共振频率）时，提取的传感信号可以最大化。该结论与介质谐振器的情况相反，并为未来器件的设计优化和灵敏度提高提供了重要指导。