Abstract
Herein, we propose a nano displacement sensor based on the interface state of a terahertz hetero-structure waveguide. The waveguide consists of two periodically corrugated metallic tubes with different duty ratios, which can result in similar forbidden bands in their frequency spectra. It was found that the topological properties of these forbidden bands are different, and the hetero-structure can be formed by connecting these two waveguides. In the hetero-structure waveguide, the interface state of an extraordinary transmission can always arise within the former forbidden bands, the peak frequency of which is highly dependent on the cavity length at the interface of the two periodic waveguides. So, by carefully designing the structure’s topological property, the hetero-structure waveguide can be efficiently used to produce a displacement sensor in the THz frequency range. The simulations show that the resolution of the displacement can be as small as 90 nm and the sensitivity can reach over 1.2 GHz/μm. Such a sensitive interface state of the proposed hetero-structure waveguide will greatly benefit THz applications of functional devices, including not only displacement sensors but also switches with high extinction ratios, tunable narrow-band filters, and frequency division multiplexers.
Highlights
In recent years, with the development of ultra-fast technologies, the research on terahertz (THz) technology has seen unprecedented progress [1,2,3,4]
The results show that all connections of different duty ratios can create a similar extraordinary transmitted peak, that is to say, the interface state between the two periodic waveguides always arises in the former Bragg gaps due to the different topologies
We proposed a micro–nano displacement sensor based on hetero-structure waveguides in the
Summary
With the development of ultra-fast technologies, the research on terahertz (THz) technology has seen unprecedented progress [1,2,3,4]. In THz imaging, displacement sensing can correct the errors of relative motion between objects and probes, and it is expected to be adopted in calibrating the amplitude of characteristic peaks for different substances. In this era of interconnection of all things, most communications depend on THz waves, and displacement sensors can be integrated into smart devices to monitor and control their position changes. The proposed hetero-structure contains a cylindrical waveguide with two different periodic corrugations on the wall Based on their different topological properties, these two periodicities are used to generate an interface state, which can be recognized by a very narrow transmitted peak in its spectrum. The major findings about the super-high resolution and sensitivity are summarized
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