基于金属基底非对称介质超光栅的太赫兹宽带吸收谱增强

打开文本图片集

中图分类号：TN214 文献标志码：A doi：10.37188/CO.2024-0197 CSTR：32171.14.CO.2024-0197

Abstract：Terahertz molecular fingerprinting isapromising method for label-free detection，particularly for micro or trace amount samples in practical applications. However，the wavelength of terahertz waves is much larger than the size of the molecules to be tested， resulting in a weak interaction between the waves and the matter. To address this challenge， additional structures are needed to enhance the absorption of electromagnetic waves by trace amount samples. In this study， we constructed an inverted asymmetric dielectric grating structure on a metal substrate.By utilizing guided-mode resonance （GMR）and a bound state in the continuum （BIC） effect， the terahertz absorption spectrum of thin film samples was significantly enhanced.The enhanced absorption spectra can be easily obtained by measuring the reflected absorption signal. The samples are coated on the flat back of the inverted dielectric grating，which simplifies the preparation process. For instance，when the thickness of an a -lactose filmis 0.2μm ，the absorption enhancement factor reaches 236. This study provides a new method for detecting trace analytes in the terahertz band.

Key words： Terahertz; fingerprint spectrum; absorption enhancement; meta-grating; metal substrate

1引言

在太赫兹波段 （0.1～10THz） ，许多分子尤其是有机及蛋白质等大分子具有独特的分子内和分子间动力学振动或旋转模式，并体现在其太赫兹指纹吸收谱的特征吸收峰形状和频率上。（剩余14446字）