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Yao Cai [1] and Yanliang He [1] and Xiaoke Zhang [1] and Rui Jiang [1] and Chenliang Su [1] and Ying Li [1]
Academic Editor: Yan Luo
SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China, szu.edu.cn
Received Jun 30, 2017; Accepted Aug 29, 2017
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Pulsed fiber lasers have been widely applied in various applications ranging within machining, material processing, environmental sensing, medicine, laser processing, fiber sensor, and long-range optical communication. The most common pulse generation methods used in fiber laser include Q-switching and mode-locking techniques [1–6]. There are two types of Q-switching approaches: active and passive one. Among them, passive Q-switching technology based on saturable absorber (SA) has made remarkable progress in view of compact, low cost, flexible, and so on. Since the Nd:glass (the first generation of SA) was successfully used for pulse generation in 1966 [7], a wide variety of SAs have been intensively developed, such as Semiconductor Saturable Absorption Mirrors (SESAMs) [8, 9], Carbon Nanotubes (CNTs) [10–13], graphene [14–18], Topological Insulator (TI) [19, 20], and Transition Metal Dichalcogenides (TMDs) [21–24]. The SESAMs are utilized in most of commercially available laser systems for high flexibility and stability. However, SESAMs have relatively narrow operation bandwidth and require complex fabrication and packaging [1]. Recently, the research on broadband SAs based on CNT or graphene has presented explosive development for broad operation bandwidth, ultrafast recovery times, low saturation intensity, low cost, and easy fabrication [10–18]. Nevertheless, they still have some drawbacks. The spectral response range of CNTs sensitively depends on their diameter and chirality, restricting their practical applications in specific wavelength or broadband tenability [13]. And, graphene has relatively weak optical absorption (~2.3%/layer [20]) due to its gapless band structure, which limits its application in fiber laser. Another 2D material, transition metal dichalcogenides (TMDs) (MoS2 [21], WS2 [22], MoSe2 [23, 24], etc.) has been developed as saturable absorber with high performances [21]. Although they have...