Fabrication of VO2 films with low transition temperature for optical switching applications

Vanadium dioxide films for optical switching applications have been prepared on Si3N4-film-coated silica substrates by ion beam sputtering from a vanadium metal target in an atmosphere of argon and oxygen and subsequent heat treatment. The as-fabricated VO2 films exhibit a nanocrystalline structure and undergo abrupt changes in electrical and optical properties with an abnormal low transition temperature of 34 °C. Using micromachining technology, applications of the films as thermo-optical switches are also demonstrated. The measured average optical isolation for the switches is 15 dB with a −2 dB insertion loss at a wavelength of 1.55 μm.