Whispering gallery modes in indium oxide hexagonal microcavities

We report on the use of In2 O3 nanowires with hexagonal cross section as optical whispering gallery resonators. The single-crystal In2 O3 nanowires were fabricated by an in situ thermal oxidation method. Whispering gallery modes (WGMs) in the visible spectral range were directly observed at room temperature. Due to the slight tapering of the nanowires, the energies and orders of the WGMs were modulated when excitations were scanned along the c -axis (length) of the nanowires. The experimental results were explained and fitted well with a plane wave interference model and Cauchy dispersion formula for refractive indices.