Abstract-Huge field enhancement and high transmittance enabled by terahertz bow-tie aperture arrays: a simulation study

Xupeng Zhu, Shi Zhang, Huimin Shi, Mengjie Zheng, Yasi Wang, Shuwen Xue, Jun Quan, Jun Zhang, and Huigao Duan

 (a) The charge distribution of a BTAAs unit cell at the feature frequencies of 1.13 THz and 1.46 THz when S = 0.04 µm, respectively. Top surface: the interface between the Au film and the vacuum. Bottom surface: the interface between the Au film and the adhesive substrate. (b) The field distribution around the feature gap size of S = 0.04 µm. Blue solid line: the line field distribution on the x-axis (y = 0). Red solid line: the line field distribution on the y-axis (x = 0).

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-4-5851

Sub-wavelength aperture arrays featuring small gaps have an extraordinary significance in enhancing the interactions of terahertz (THz) waves with matters. But it is difficult to obtain large light-substance interaction enhancement and high optical response signal detection capabilities at the same time. Here, we propose a simple terahertz bow-tie aperture arrays structure with a large electric field enhancement factor and high transmittance at the same time. The field enhancement factor can reach a high value of 1.9×104 and the transmission coefficient of around 0.8 (the corresponding normalized-to-area transmittance is about 14.3) at 0.04 µm feature gap simultaneously. The systematic simulation results show that the designed structure can enhance the intensity of electromagnetic hotspot by continuously reducing the feature gap size without affecting the intensity of the transmittance. We also visually displayed the significant advantages of extremely strong electromagnetic hot spots in local terahertz refractive index detection, which provides a potential platform and simple strategy for enhanced THz spectral detection.

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