title: Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers.
abstract: Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm(2) at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices.
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Jin-Long
authors.initials: JL
authors.lastname: Xu
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Yi-Jian
authors.initials: YJ
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, China.
authors.forename: Jing-Liang
authors.initials: JL
authors.lastname: He
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Zhao-Jie
authors.initials: ZJ
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: You
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Jian-Fu
authors.initials: JF
authors.lastname: Li
authors.affiliation: Department of Materials and Optoelectronics Science, National Sun Yat-sen University, 70, Lienhei Road, Kaohsiung, Taiwan.
authors.forename: Mitch M C
authors.initials: MM
authors.lastname: Chou
authors.affiliation: Department of Photonics, National Sun Yat-sen University, 70, Lienhei Road, Kaohsiung, Taiwan.
authors.forename: Chao-Kuei
authors.initials: CK
authors.lastname: Lee
authors.affiliation: Key Laboratory of Optoelectronic Materials Chemistry and Physics of CAS, Fujian Institute of Research on the Structure of Matter, Chinese Academic of Sciences, Fuzhou, 350002 China.
authors.forename: Chao-Yang
authors.initials: CY
authors.lastname: Tu