Wang Yue, Chen Wenshuo, Cui Zijian, Sun Guangcheng, Zhang Kuang
Opt Lett. 2024 May 1;49(9):2477-2480. doi: 10.1364/OL.522765.
The terahertz absorption fingerprint spectrum is crucial for qualitative spectral analysis, revealing the rotational or vibrational energy levels of numerous biological macromolecules and chemicals within the THz frequency range. However, conventional sensing in this band is hindered by weak interactions with trace analytes, leading to subtle signals. In this Letter, an all-dielectric metasurface array is proposed to enhance the absorption fingerprint spectrum using quasi-bound states in the continuum (BIC) resonance. The observable quasi-BIC resonance is achieved by breaking the symmetry of the Cv structure. The periodic dimensions of the structure are adjusted to excite quasi-BIC resonances at different frequencies, thereby enhancing the fingerprint spectra of four different substances. By exploiting the correlation between the Q-factor and absorption across different frequencies, calibration of the molecular absorption fingerprint spectrum obtained through metasurface sensing yields precise enhanced absorption fingerprint spectra for various substances within the 0.55-1.6 THz range. Our Letter introduces a novel, to the best of our knowledge, strategy for trace sensing in the THz frequency range, demonstrating the promising potential for enhanced absorption fingerprint spectrum sensing.
太赫兹吸收指纹光谱对于定性光谱分析至关重要，它能揭示太赫兹频率范围内众多生物大分子和化学物质的转动或振动能级。然而，该频段的传统传感因与痕量分析物的相互作用较弱而受到阻碍，导致信号微弱。在本信函中，提出了一种全介质超表面阵列，利用连续谱中的准束缚态（BIC）共振来增强吸收指纹光谱。通过打破Cv结构的对称性实现了可观测的准BIC共振。调整结构的周期尺寸以在不同频率激发准BIC共振，从而增强四种不同物质的指纹光谱。通过利用不同频率下品质因数与吸收之间的相关性，对通过超表面传感获得的分子吸收指纹光谱进行校准，可在0.55 - 1.6太赫兹范围内为各种物质产生精确的增强吸收指纹光谱。据我们所知，本信函介绍了一种太赫兹频率范围内痕量传感的新策略，展示了增强吸收指纹光谱传感的广阔前景。
