Enhanced amplitude modulation of a terahertz complementary vanadium dioxide metamaterial*

Vanadium dioxide (VO₂) is a dynamic quantum material that undergoes an insulator-to-metal transition (IMT) at ~340K. Integration with metamaterials yields enhanced manipulation and control of terahertz radiation which enables, as but two examples, signal modulation and tunable absorption. We introduce a complementary split ring resonator (CSRR) array integrated with a VO₂ film that provides greatly increased transmission modulation at terahertz (THz) frequencies in comparison to either bare VO₂ films or conventional split ring resonator arrays integrated with VO₂. The amplitude modulation at ~0.5 THz is increased from 0.42 for the bare VO₂ film to 0.68 for the metamaterial composite, corresponding to a 62.4% enhancement. Moreover, temperature dependent transmission measurements reveal a redshift of the resonant frequency upon traversing the IMT. Maxwell-Wagner modeling suggests that the origin of this redshift arises from a percolation induced permittivity increase in VO₂ during the IMT. Our work provides a route to obtain dynamic enhancement and dielectric sensitivity that facilitates the development of tunable devices and provides a simple and effective means to investigate the local electrodynamic properties of quantum materials.