Two-photon absorption within layered BiTe topological insulators and the role of nonlinear transmittance therein

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2019-06, Vol.7 (23), p.727-734
• Main Authors: Qiao, Junpeng, Chuang, Meng-Yuan, Lan, Jia-Chi, Lin, Yuan-Yao, Sung, Wei-Heng, Fan, Ranran, Wu, Meng-Yu, Lee, Chi-Yang, Chen, Chun-Hu, Liu, Hong, Lee, Chao-Kuei
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c9tc01885a

In this study, strong two-photon absorption (TPA) in a layered bismuth telluride (Bi 2 Te 3 ) topological insulator (TI) is observed and investigated by the Z-scan method under excitation with a femtosecond laser pulse at a wavelength of 1056 nm. Nonlinear transmission measurements reveal that Bi 2 Te 3 possesses not only the property of single photon absorption (SPA) but also the effect of TPA. A saturation TPA coefficient as high as ∼2.29 × 10 6 cm GW −1 has been obtained, which is at least two orders of magnitude higher than that of other two dimensional (2D) materials, such as MoS 2 . The large TPA effect in the Bi 2 Te 3 TI is attributed to the existence of high-lying bulk states located above the first bulk state. Meanwhile, it can also be used to explain the discontinuity of the optical nonlinear transmittance between the low and high excitation energy regions. In this study, strong two-photon absorption (TPA) in a layered bismuth telluride (Bi 2 Te 3 ) topological insulator (TI) is observed and investigated by the Z-scan method under excitation with a femtosecond laser pulse at a wavelength of 1056 nm.