Optimization of Modulation Properties of Terahertz Metamaterial by Tuning Fabry–Pérot Resonances

In this work, we investigate the transmission properties of planar arrays of split-ring resonators formed on the surface of a dielectric plate. The modulation concept is demonstrated by using several metamaterial structures with a different effective capacitance of the split gap, thus imitating a metamaterial of tunable frequency. The proposed modulation scheme can be employed in the fabrication of a fast narrow-band terahertz modulator. The influence of Fabry-Pérot resonances in the dielectric substrate on the parameters of the possible metamaterial-based modulator is analyzed in the terahertz region. Our results demonstrate that tuning the dielectric plate parameters allows for the optimization of the modulator performance. The presented modulation scheme based on frequency-tunable metamaterial offers a high modulation depth (95% at 425 GHz) with the resonant frequency tuning as small as ~ 15%. Measurement results are found in agreement with calculations.