Gavdush A A, Chernomyrdin N V, Lavrukhin D V, Cao Yang, Komandin G A, Spektor I E, Perov A N, Dolganova I N, Katyba G M, Kurlov V N, Ponomarev D S, Skorobogatiy M, Reshetov I V, Zaytsev K I
Opt Express. 2020 Aug 31;28(18):26228-26238. doi: 10.1364/OE.401608.
A continuously-tunable terahertz (THz) bandpass filter based on the resonant electromagnetic-wave transmission through a metal-hole array featuring a gradually changing period was developed and fabricated on a silicon substrate using optical lithography. A gradient geometry of the metal-hole array yields a wide tunability of the filter transmission, when operating with a focussed THz beam. The filter was studied numerically, using the finite element method, and experimentally, using the THz pulsed spectroscopy. We find that the central wavelength of the filter transmission band can be tuned in the wide range of λ = 400-800 μm with the relative bandwidth of Δλ/λ ≃ ~0.4. Finally, Kapton-based anti-reflection coating was applied to the filter flat side, in order to suppress an interference pattern in the filter transmission spectrum. We believe that the developed filter holds strong potential for multispectral THz imaging and sensing due to its conceptual simplicity and case of operation. Moreover, the presented filter concept can be translated to other spectral ranges, where appropriate technologies are available for the fabrication of gradient sub-wavelength metal-hole arrays.
基于通过具有逐渐变化周期的金属孔阵列的共振电磁波传输，在硅衬底上利用光刻技术研制并制造了一种连续可调太赫兹（THz）带通滤波器。当使用聚焦太赫兹光束时，金属孔阵列的梯度几何结构可实现滤波器传输的宽可调性。使用有限元方法对该滤波器进行了数值研究，并使用太赫兹脉冲光谱进行了实验研究。我们发现，滤波器传输带的中心波长可在λ = 400 - 800μm的宽范围内调谐，相对带宽为Δλ/λ≃~0.4。最后，在滤波器平面侧涂覆了基于聚酰亚胺的抗反射涂层，以抑制滤波器传输光谱中的干涉图案。我们认为，由于其概念简单和操作简便，所研制的滤波器在多光谱太赫兹成像和传感方面具有巨大潜力。此外，所提出的滤波器概念可推广到其他光谱范围，只要有合适的技术可用于制造梯度亚波长金属孔阵列。
