A near-perfect THz modulator enabled by impedance matching method with VO2 thin films

摘要

We present a terahertz (THz) amplitude modulator with near perfect modulation depth based on the impedance matching method during the thermally induced insulator-metal transition (IMT) of VO₂ thin films. It has been observed that the impedance matching-induced THz amplitude modulation was sensitive to the resistance switching characteristics of the VO₂ thin films. With four orders of change in resistance of the properly designed VO₂ films during the IMT, we experimentally achieved a near perfect THz modulator with an intensity modulation depth of 99.7^% between the insulator phase of VO₂ and the impedance matching state, and intensity modulation depth of 99.94% between the impedance matching state and the metallic phase of VO₂. The experimental results were well explained by numerical simulations based on the transfer matrix model.