Optical Properties of VO2 Nanosphere with Phase Transition

In this paper the optical properties of the homogeneous nonmagnetic vanadium dioxide (VO2) nanosphere embedded in the air and also size effect on these characteristics are studied. VO2 is an insulator at room temperature and becomes metal above a critical temperature (Tc=341K). In the metallic phase, a localized surface plasmon resonance (LSPR) forms in VO2 nanosphere, which red shifts slightly by increasing dimension, its associated electric field is in form of dipole, and disappears in insulator phase. The increment in the dimension of nanosphere in insulator case, results in the appearance of a peak in the visible wavelength that its origin is combined modes. VO2 nanosphere in metallic case has much broader optical spectra in comparison to silver (Ag) nanosphere, as well as, the electric field of Ag nanosphere in LSPR is more intense than its counterpart in VO2. Nevertheless the LSPR of VO2 can be switched thermally, making this material peculiar in optical applications.