Mechanically tunable multi-band terahertz absorber based on overlapping graphene nanoribbon arrays

Abstract

With promising applications in broadband communication, terahertz (THz) imaging, biochemical sensing, nondestructive testing and other fields, THz absorbers have become a hot research topic in recent years. Although a number of graphene-based multi-band THz absorbers with tunable performances have been reported, the tuning methods are mostly limited to electrical tuning. Here, we report a mechanically tunable multi-band THz absorber, which is based on overlapping graphene nanoribbon arrays. By adjusting the horizontal position of the upper cover plate with graphene nanoribbon array, the frequencies of the absorption peaks can be tuned in a wide range. In addition to the absorption peaks originating from even-order lateral Fabry-Pérot resonance (LFPR) modes, there are also absorption peaks originating from inductor-capacitor (LC) oscillations. An equivalent LC circuit model is developed and theoretical results match well with simulated values. The proposed mechanically tunable THz absorber may provide a reference for tunable THz absorbers that can be applied in various fields.