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

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 VO
₂
thin films. It has been observed that the impedance matching-induced THz amplitude modulation was sensitive to the resistance switching characteristics of the VO
₂
thin films. With four orders of change in resistance of the properly designed VO
₂
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 VO
₂
and the impedance matching state, and intensity modulation depth of 99.94% between the impedance matching state and the metallic phase of VO
₂
. The experimental results were well explained by numerical simulations based on the transfer matrix model.