Research Institute of Physics and other two-dimensional nanomaterials mode-locked all-fiber laser research progress
Ultrashort pulse laser has the advantages of high peak power, short action time, wide spectrum, etc. It has been widely used in basic science, medical treatment, aerospace, quantum communication, military and other fields. In particular, the rapid development of femtosecond fiber lasers in recent years has shown more and more extensive application prospects because of its simple structure, low cost, high stability, and portability. At present, fiber-mode-locked lasers, including other types of solid-state lasers, need to rely on saturable absorbers in order to achieve stable mode-locking operation. However, due to problems such as laser damage and loss caused by saturable absorbers, not only Limiting the laser pulse width and power that can be generated will also affect the reliability of long-term operation. Therefore, the research and development of new saturable absorbers with high damage threshold and low loss has attracted the attention of laser experts and material experts. In the past decade and more, with the development of condensed matter physics and material preparation technology, carbon nanotubes, graphene, and topological insulators have been used successfully in laser mode-locking as saturable absorbing materials, especially newly developed. Two-dimensional nanomaterials exhibit excellent saturable absorption characteristics because of their narrow bandgap, ultrafast electron relaxation time, and high damage threshold. Research on mode-locked lasers using this material has also become one of the hot topics that people are paying close attention to. .
The Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics (Group) L07 Group of Optical Physics Key Laboratory has always been devoted to the research of ultrafast lasers. In recent years, for the development of miniaturized femtosecond lasers, many types of crystals have been realized. Saturable absorption of fiber lasers Passive mode locking. By using the pulsed laser deposition method, the cesium-suppressed top insulator material is uniformly grown on the saturable absorber formed on the surface of the tapered optical fiber, and the fiber laser is first mixed and mode-locked, and a 70 fs output pulse result is obtained. By using tungsten disulfide with ultrashort electron relaxation time as a saturable absorbing material, combined with a reduction in the core diameter of the tapered fiber, a 67 fs mode-locked pulse output was obtained, verifying that the hybrid mode-locked fiber laser has a pulse width Shorter, less timing jitter and other advantages. In addition, according to the limitation of dark soliton generation technology, the relationship between gain, loss, dispersion and nonlinearity of fiber laser in the Ginzburg-Landau equation is theoretically calculated. The dynamic mechanism of dark soliton pulse formation is theoretically analyzed and the signal to noise ratio is obtained. Up to 94 dB results, experimentally the darkest soliton pulse output of the widest spectrum was achieved.
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 pulsed laser output with a pulse width of 246 fs. It is known that this is the transition metal sulphide The shortest pulse width reported by the fiber-mode-locked laser is reported. The relevant results were published in the new issue of Nanoscale (2017, 9: 5806) and selected by the magazine as Highlights as Inside front cover paper (as shown). The first author of the paper is Liu Wenjun, Corresponding Author Professor Lei Ming from Beijing University of Posts and Telecommunications and Wei Zhiyi, a researcher at the Institute of Physics, Chinese Academy of Sciences.
This research was supported by the "973" project of the Ministry of Science and Technology (2012CB821304) and the National Natural Science Foundation of China (Grant Nos. 11674036, 11078022, and 61177040).
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