IR-wavelength optical shutter based on ITO/VO₂/ITO thin film stack

Two thin film IR-shutter structures based on ITO-VO₂-ITO and ITO-VO₂ thin film stacks were designed. Thin film structures of the shutters were optimized at the wavelength of 1550 nm. The switch operation of the components was based on the metal-insulator transition phenomenon of VO₂. Shutter components were current controlled and the metal-insulator transition was induced by Joule heating effect. All the thin films were deposited by using pulsed laser deposition. Crystal structure, morphology, and optical characteristics of the produced components were studied. Components with three-layer structure were found to suffer from significant internal strain, which was relaxed by post-annealing the components in the furnace. The maximum change of the optical transmittance measured at the wavelength of 1550 nm from the three-layer components during the switch cycle was 26.5%. The corresponding value measured from two-layer component’s structure was 34.2%. The maximum modulation of the transmittance of the three-layer component was reached at the wavelength of 1250 nm, which was 34%.