Photo-induced structured waves by nanostructured topological insulator Bi₂Te₃

Third-order nonlinear optical effects were proposed for simultaneous speed modulation of optical and mechanical waves in bismuth telluride nanostructures assisted by an optical two-wave mixing. The optical nonlinearities were investigated under excitation with nanosecond laser pulses at a wavelength of 532 nm. The Bi₂Te₃ nanostructures were prepared by a simple chemical process. Standard characterization by electrochemical impedance spectroscopy, ellipsometry, UV–Vis absorption and Fourier transform infrared spectrometry was undertaken. The phase purity and vibrational mode of the Bi₂Te₃ were determined by X-ray diffraction studies and Raman spectroscopy, respectively. The nanocrystal structure and morphology of the Bi₂Te₃ sample were identified by High-Resolution Transmission Electron Microscopy. The structural characterization and chemical composition of the nanostructures were carried out by Scanning Electron Microscopy combined with Energy Dispersive X-ray spectroscopy. The nanostructured nature of this topological insulator seems to be responsible of its unique polarization-selectable nonlinear optical response. Potential applications for developing structured light systems can be contemplated.