Photo-oxidation-modulated refractive index in Bi2Te3 thin films

Authors

Zengji Yue, Royal Melbourne Institute of TechnologyFollow
Qinjun Chen, Hunan UniversityFollow
Amit Sahu, Swinburne University of Technology
Xiaolin Wang, University of WollongongFollow
Min Gu, Royal Melbourne Institute Of Technology

RIS ID

118247

Publication Details

Yue, Z., Chen, Q., Sahu, A., Wang, X. & Gu, M. (2017). Photo-oxidation-modulated refractive index in Bi2Te3 thin films. Materials Research Express, 4 (12), 126403-1-126403-5.

Abstract

We report on an 800 nm femtosecond laser beam induced giant refractive index modulation and enhancement of near-infrared transparency in topological insulator material Bi₂Te₃ thin films. An ultrahigh refractive index of up to 5.9 was observed in the Bi₂Te₃ thin film in near-infrared frequency. The refractive index dramatically decreases by a factor of ~3 by an exposure to the 800 nm femtosecond laser beam. Simultaneously, the transmittance of the Bi₂Te₃ thin films markedly increases to ~96% in the near-infrared frequency. The Raman spectra provides strong evidences that the observed both refractive index modulation and transparency enhancement result from laser beam induced photooxidation effects in the Bi₂Te₃ thin films. The Bi₂Te₃ compound transfers into Bi₂O₃ and TeO₂ under the laser beam illumination. These experimental results pave the way towards the design of various optical devices, such as near-infrared flat lenses, waveguide and holograms, based on topological insulator materials.