Saturated absorption of different layered Bi2Se3 films in the resonance zone
Here, we used the micro P-scan method to investigate the saturated absorption (SA) of different layered Bi2Se3 continuous films. Through resonance excitation, first, we studied the influence of the second surface state (SS) on SA. The second SS resonance excitation (～2.07 eV) resulted in a free carrier cross section that was 4 orders of magnitude larger than usual. At the same time, we found that the fast relaxation process of the massless Dirac electrons is much shorter than that of electrons in bulk states. Moreover, the second SS excitation resonance reduced the saturation intensity. Second, we studied the effect of the thickness on the SA properties of materials. The results showed that the saturation intensity was positively correlated to the thickness, the same as the modulation depth, and the thicker the Bi2Se3 film was, the less the second SS would influence it. This work demonstrated that by using Bi2Se3 as a saturable absorber through changing the thickness or excitation wavelength, a controllable SA could be achieved.
基金项目：Opening Foundation of State Key Laboratory of High Performance Computing (201601-01, 201601-02, 201601-03); Scientific Researches Foundation of National University of Defense Technology (zk16-03-59); Open Research Fund of State Key Laboratory of Pulsed Power Laser Technology (SKL2017KF06); Funds for International Cooperation and Exchange of National Natural Science Foundation of China (NSFC)10.13039/501100001809 (60921062, 61120106); Director Fund of State Key Laboratory of Pulsed Power Laser Technology (SKL2018ZR05).
Tian Jiang：College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
Tong Zhou：State Key Laboratory of High Performance Computing, National University of Defense Technology, College of Computer, Changsha 410073, China
Hao Ouyang：College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
Chenxi Zhang：College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
Zheng Xin：National Institute of Defense Technology Innovation, Academy of Military Sciences PLA China, Beijing 100010, China
Zhenyu Wang：National Institute of Defense Technology Innovation, Academy of Military Sciences PLA China, Beijing 100010, Chinae-mail: email@example.com
Xiang’ai Cheng：College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China
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Jun Zhang, Tian Jiang, Tong Zhou, Hao Ouyang, Chenxi Zhang, Zheng Xin, Zhenyu Wang, and Xiang’ai Cheng, "Saturated absorption of different layered Bi2Se3 films in the resonance zone," Photonics Research 6(10), C8 (2018)