Theoretical analysis of InAs based Bi-tunable narrow band terahertz perfect absorber for thermal sensing application

Abstract

In this paper, a bi-tunable metamaterial absorber comprising a subwavelength resonator of semiconducting material InAs and a metallic plane adhered to a dielectric layer has been proposed in the terahertz regime. Absorption of about 99.8 % is achieved at 4.446 THz with the application of magnetic field B = 0.4 T and a high tunability rate of 0.4 THz/T in the central resonance frequency due to the presence of a magnetostatically tunable H-shaped InAs resonator and polyimide dielectric layer. The same structure supports dual control over the resonance by replacing polyimide dielectric layer with InSb, as InSb possesses temperature- and magnetic field-dependent dielectric properties. The replacement of polyimide dielectric layer with InSb provides near unity absorption of 99.99 % at B = 0.4 T but when the effect of temperature on the absorption is taken, it provides a high absorptivity of 99.99 % at T = 285 K with a blue shift in the maximum resonance frequency, providing tunability of 0.016 THz/K on increasing the temperature from 280 K to 295 K. Thus, the proposed absorber not only provides dual control over the resonance spectrum but also progresses towards more practical applications in the sensing and detection of temperature variance.