Abstract Terahertz (THz) plasmonic sensors has been regarded as exciting advances in biomedical engineering, due to their real-time, label-free, and ultrasensitive monitoring features. But actually, its widespread application remains impeded by poor modulation properties of operating frequency, single amplitude characterization method, and limited to low-loss substances. In the work, an ultraprecision THz sensor is achieved with direct phase readout capacity via combining steerable plasmonic resonance and attenuated total reflection. Interestingly, the oft-neglected THz phase were found to be ideal for plasmonic sensing characterization. Detailed investigation shows that the reflected THz phase exhibits two entirely different jump responses to coupling gap. Remarkably, the Q-factor of phase spectra for optimal coupling gaps, are generally higher than that of fixed coupling gaps, which falls within the range of 9.7–43.4 (4–26 times higher than its counterpart in amplitude measurements) in liquids sensing. The unique phase-jump responses on metasurfaces pave the way for novel THz sensing methods.

中文翻译：

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用于液体传感的太赫兹等离子体相跃机械手

摘要 太赫兹 (THz) 等离子体传感器由于其实时、无标记和超灵敏的监测特性，被认为是生物医学工程中令人兴奋的进步。但实际上，其广泛应用仍然受到工作频率调制特性差、单幅表征方法和仅限于低损耗物质的限制。在这项工作中，通过结合可控等离子体共振和衰减全反射，实现了具有直接相位读出能力的超精密太赫兹传感器。有趣的是，发现经常被忽视的太赫兹相位是等离子体传感表征的理想选择。详细调查表明，反射的太赫兹相位对耦合间隙表现出两种完全不同的跳跃响应。值得注意的是，最佳耦合间隙的相位谱的 Q 因子，通常高于固定耦合间隙的值，固定耦合间隙在液体传感中落在 9.7-43.4（比幅度测量中的对应值高 4-26 倍）范围内。超表面上独特的相位跳跃响应为新型太赫兹传感方法铺平了道路。