Optical Switching in VO2 films by below-gap excitation
- Rini, Matteo;
- Dipartimento di Fisica, Universita? di Brescia, Italy;
- Universite du Quebec, INRS energie et materiaux, Varennes, Quebec;
- Department of Physics. Clarendon Laboratory, University of Oxford, UK;
- Department of Physics, University of Tokyo;
- Institute of Physics, University of Tsukuba, Ibaraki, Japan
We study the photo-induced insulator-metal transition in VO2, correlating threshold and dynamic evolution with excitation wavelength. In high-quality single crystal samples, we find that switching can only be induced with photon energies above the 670-meV gap. This contrasts with the case of polycrystalline films, where formation of the metallic state can also be triggered with photon energies as low as 180 meV, well below the bandgap. Perfection of this process may be conducive to novel schemes for optical switches, limiters and detectors, operating at room temperature in the mid-IR.