Programming optical states in VO2 film for IR phototherapy

This work presents a new technology suitable for localized infrared (IR) phototherapy. Specified regions of a VO₂ thin film were programmed to different transmissivity values in the near IR. Such programming was done through photothermal actuation of the thin film, achieved by controlling the scanning of a red laser over its surface. The thermally-induced phase transition of the VO₂ thin film comes with an abrupt change in its transmittance, which (due to its hysteretic behavior) can be stored; allowing for the programming of optical memory states in the films. Several patterns were stored and read through a simple optical system. A single film can store one pattern at a time. The nature of this material allows for a relatively fast reconfiguration of the stored pattern. After a specific pattern was programmed on the film, an IR image was projected by illumination of the entire VO₂ film with an IR beam. The image was detected by a laser beam profiler (LBP). This pattern storage and projection technology proves promising in the development of applications for treatments of IR phototherapy.