Laser induced the tunable permittivity of Epsilon-Near-Zero induced in indium tin oxide thin films

Tunable permittivity of Epsilon-Near-Zero (ENZ) of ITO thin films were realized by Nd: YAG pulse laser irradiation. The effects of different pulsed laser power irradiation on the structure, morphology and optical properties of the samples were investigated via X-ray diffraction, atomic force microscopy, UV-VIS-NIR double beam spectrometer, spectroscopic ellipsometry and Raman system, respectively. Those results indicate that pulse laser irradiation has the effects on the preferential orientation and the permittivity wavelength region of ENZ from 1137 to 2001 nm. The variations of Raman spectra further confirms that the laser irradiation can induce some defects driving the special optical characteristics of ITO films. In addition, the results of Finite-Difference Time-Domain are in good agreement with those of the experiments.