Design of dual-layer serpentine-shaped metamaterial with tunable resonant infrared wavelength and spectra intensity

Abstract

We present a design of dual-layer serpentine-shaped metamaterials (SSM) in the infrared (IR) wavelength range. It is composed of one serpentine-shaped gold (Au) nanostructure array on silicon (Si) substrate and another serpentine-shaped Au nanostructure array suspended atop. SSM device shows multi-resonance in the wavelength range from 1 μm to 3 μm in transverse electric (TE) and transverse magnetic (TM) modes. By changing the gap of top SSM layer, the resonance at the wavelength of 1.15 μm can be modulated from 23% to 47% and that at the wavelength of 1.78 μm can be modulated from 82% to 2% in TE mode. In TM mode, the tuning ranges of two resonances are over 80%. Moreover, the proposed SSM design is sensitive to the polarization angle of incident wave, which shows switching characteristics at resonant wavelengths under the conditions of different polarization angles. To increase the flexibility and applicability of SSM device, it is exposed on the ambient environment with different refractive indexes. The relationships of resonances and refractive indexes are quite linear. Hence, the SSM device exhibits the potential application to be used to realize logic devices, switchable optic devices, environmental detectors, tunable filters and so on.