A novel dual-band terahertz metamaterial modulator

This paper presents a novel terahertz (THz) dual-band metamaterial modulator on a gallium arsenide (GaAs) substrate with an n-type GaAs epitaxial layer. By adopting split strips of two different lengths in one cell of metamaterial structure, the metamaterial can resonate at 0.58 THz and 1.0 THz. The electric-controlled depletion region of Schottky contacts is numerically analyzed to explain the mechanism of modulator and estimate the modulation depths. The measurements show that the modulation depths at the resonant frequencies (0.61 THz and 1.03 THz) can reach 50% and 85% under an inverse bias of 17 V in good agreement with simulations. The surface plasmons are utilized to explain the difference of modulation depths at two bands, and the tri-band modulator is also discussed for the scalability of the metamaterial structure. The presented dual-band modulator can help to design THz modulators with multi-band modulations and high modulation depths.