A metal-insulator-metal voltage tunable filter based on organic electro-optical materials DAST is proposed by using the side-coupled method. The structure consists of two H-type cavities and a rectangular waveguide. The transmission spectra, resonance wavelength distribution curves and the magnetic field distribution of the asymmetric H-type cavities structure filter have been calculated and analyzed by the finite element numerical simulation method. The results show that the filter has the feature of smooth transmission spectra, wide bandwidth (full width at half maxima achieved 754 nm). And the transmittance of the passband is up to 0.968, the transmittance of the stopband can reach 1 × 10−5. The characteristics of the filter can be adjusted not only by changing the structural parameters, but also by applying a control voltage, the adjustability of the filter is increased. Therefore, the filter is of great significance in high-density integrated circuits and nano-optics.
In this paper, a terahertz absorber based on monolayer graphene is proposed. This absorber consists of a monolayer graphene and a micro-nano structure which is composed of a gold layer and silicon dioxide-silicon layer. The combination of the monolayer graphene and the simple micro-nano structure makes this absorber easy to fabrication in engineering. The introduction of the monolayer graphene also enhances the coherent superposition of incident and reflected light and results in a significant increase in the absorption of this proposed absorber. The absorber can achieve perfect absorption. When the thicknesses of gold, silicon dioxide and silicon are set to 5 um, 5.4 um, 2.3 um respectively, at the same time the incident wave is normal incidence, the maximum absorption at the absorption frequency of 5.605 THz is 0.997 and the full width at half maximum is 2.22 THz. In addition, the absorber has polarization independent and large angle absorption characteristics due to its highly symmetrical structure. These advantages make it has a great application prospect in the fields of photoelectric detection, photoelectric modulation and solar cells.