Rene Lopez

Home | Applied Optics Group | Research | Physics 117B summer | Personal webpage

Nonlinear optics on VO2

The semiconductor-to-metal phase transition can easily be excited by an ultrafast laser pulse. In the following image, this process is illustrated in thin films and small nanoparticles.

This laser excited phase transiton can be treated like a nonlinear absoprtion. a z-scan of a thin film illustrate the change in transmittance as the fluence of the laser is increased near the focal spot.

This effect is present in films and nocrystals the same. However, important differences can be found in the magnitud and sign of the equivalent nonlinear index. Next figure illustrate the point. z-scan curves at the bottom correspond the a VO2 thin film and curves at the top correspond to a nanoparticle system