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Terahertz sensing is one of the most promising methods for label-free and noninvasive detection of refractive index changes. However, the figure of merit (FOM) of terahertz sensors in practical applications has been low. In this paper, a metamaterial sensor based on simple stacking of gold and silicon dioxide is proposed, through whose structure not only narrow-band absorption with five absorption peaks is realized, but FOM is also improved to 1792. The excellent sensing performance and the mature manufacturing technology of this kind of structure provide a platform for the design of multi-band photodetectors and high-sensitivity sensors. [ABSTRACT FROM AUTHOR]

We propose a composite metasurface composed of InSb strips and SiO2 substrate, which can achieve multi-band coherent perfect absorption in the terahertz frequency range. It is demonstrated that InSb strips of different sizes support independent plasmon resonances at different frequencies, which is a linear superposition of each subunit. The absorption at each resonance frequency can be independently and continuously modulated with the modulation depth is up to 1.332 × 104 via controlling the relative phase or relative intensity of two beams. Meanwhile, the absorber has the sensitivity of the refractive index to the surrounding environment, thereby facilitating the design of sensing devices. Moreover, it has excellent thermal tunability: we flexibly modulate absorption via controlling the temperature without restructuring. Our design contributes a feasible way of manipulating the interaction between light and matter, which can be applied to the field of micro–nano photonic devices in the terahertz band. [ABSTRACT FROM AUTHOR]

In this paper, we present an easy-to-implement metamaterial absorber based on bulk Dirac semimetal (BDS). The proposed device not only obtains an ultrahigh quality factor (Q-factor) of 4133 and dynamic adjustability at high absorption, but also exhibits an excellent sensing performance with a figure of merit (FOM) of 4125. These outstanding properties are explained by the surface lattice resonance, which allows us to improve the quality factor significantly and control resonance wavelength precisely by tuning the unit cell periods, Fermi energy of the BDS, and structural parameters. Our findings can provide high-performance applications in terahertz filtering, detection, and biochemical sensing. [ABSTRACT FROM AUTHOR]