Ultrabroadband mid-infrared pump-probe spectroscopy in Bi2Te2Se
Tien-Tien Yeh1*, Chih-Wei Luo1, Hideto Shirai2, Takao Fuji2, Fang-Cheng Chou3
1Department of Electrophysics, National Chiao-Tung University, Hsinchu, Taiwan
2Institute for Molecular Science, Okazaki, Japan
3Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
* presenting author:葉恬恬, email:jiljiljilji@gmail.com
We report on the ultrafast dynamics of topological insulator Bi2Te2Se crystals by using optical pump ultra-broadband mid-infrared probe spectrocsopy. After pumping with the photon energy of 1.55 eV and fluence of 67 μJ/cm2, the reflected intensity of mid-infrared probe pulses, generated by the four wave mixing, on a sample can be measured by using chirp pulse up-conversion and a visible dispersive spectrometer. The complete ultrafast carrier dynamics in topological insulators can be clearly resolved by the broad MIR detection range from 500 to 5000 cm-1 and discussed detailedly.

Keywords: topological insulator, ultrafast dynamics, pump-probe spectroscopy, carrier dynamics, four-wave mixing generation