Electrically Tunable Graphene-on-Polyimide Terahertz Modulators

We report a graphene-on-polyimide THz modulator with a tunable-by-design optical bandwidth, a 90% modulation efficiency, a 20 KHz electrical bandwidth and tunable in the 1.9-2.7 THz range. The electrostatic tuning of the THz conductivity is achieved through a grating gate coupler on the top of the polyimide waveguide. By coupling the modulator with a THz quantum cascade laser frequency comb, we show it can fully compensate the cavity dispersion, resulting in stable frequency comb operation over a 45% dynamic range.