Ultrashort pulse laser has the advantages of high peak power, short acting time and wide spectrum. It has been widely used in basic science, medical treatment, aerospace, quantum communication and military fields. Especially in recent years, the rapid development of femtosecond fiber lasers due to simple structure, low cost, high stability and easy to carry and so on, showing more and more extensive application prospects. At present, fiber-mode-locked lasers, including other types of solid-state lasers, have to rely on saturable absorbers for more stable mode-locking operation. However, due to issues such as laser damage and loss caused by saturable absorbers, not only Constrained by the laser pulse width and power can also affect the reliability of long-term operation. Therefore, research and development with high damage threshold and low loss of a new type of saturable absorber, much attention by laser experts and material experts. In recent ten years, with the development of condensed matter physics and material preparation technology, materials such as carbon nanotubes, graphene and topological insulators have been successfully used in laser mode-locking as saturable absorbing materials, especially in the newly developed Two-dimensional nanomaterials exhibit excellent saturable absorption characteristics due to their narrow bandgap, ultra-fast electron relaxation time and high damage threshold, and the research on mode-locked laser using this material has also become one of the hot topics of great interest .
Institute of Physics, Chinese Academy of Sciences / Key Laboratory of Photophysics, Beijing Condensed Matter Physics Laboratory L07 has been devoted to the research of ultrafast laser. In recent years, the development of miniature femtosecond laser has realized many kinds of crystals Fiber laser saturable absorption passive mode-locking. The pulsed laser deposition method was used to uniformly mix the antimony telluride topological insulator material on the saturable absorber formed on the surface of the tapered fiber. The mixed mode-locked fiber laser was achieved for the first time, and the output pulse of 70 fs was obtained. A 67 fs mode-locked pulse output was obtained by using tungsten disulfide with ultra-short electron relaxation time as a saturable absorbing material in combination with decreasing the core diameter of a taper fiber. It was verified that the mixed mode-locked fiber laser has a pulse width Shorter, lower timing jitter and so on. In addition to the limitation of dark soliton generation technology, the dynamics mechanism of dark soliton pulse formation is theoretically analyzed by theoretically calculating the relationship of gain, loss, dispersion and nonlinearity of fiber laser in Ginzburg-Landau equation, and the signal-to-noise ratio Up to 94 dB results, experimentally achieved the broadest spectral dark soliton pulse output.
The paper "Nanoscale" (2017, 9: 5806) is selected for this issue of the Inside front cover paper.
Recently, the research group cooperated with Beijing University of Posts and Telecommunications to use tungsten disulfide as a saturable absorbing material for fiber laser mode-locking and further realized a mode-locked pulse laser output with a pulse width of 246 fs. It is known that this is by far the most complete transition metal sulfide Fiber mode-locked laser produced by the shortest pulse width reported. Relevant results were published in a newly published issue of Nanoscale (2017, 9: 5806) and selected as a Highlights by the magazine as an Inside front cover paper (as shown in Figure 1). The lead author of the paper was Liu Wenjun Ph.D., Corresponding author: Professor Lei Ming from Beijing University of Posts and Telecommunications and researcher Wei Zhiyi from the research group of Institute of Physics, Chinese Academy of Sciences.
The research was supported by the Ministry of Science and Technology 973 Project (2012CB821304) and the National Natural Science Foundation of China (Grant Nos., and).
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