2D Nanofiber All-Fiber Mode-Locked Laser Research Progress Made by the Chinese Academy of Sciences

【Chinese instrument network instrument research and development】 Ultrashort pulse laser has the advantages of high peak power, short action time, wide spectrum, etc. It has a wide range of applications in basic science, medical, aerospace, quantum communications, military and other fields.

The rapid development of femtosecond fiber lasers in recent years has become more and more widely used 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 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, with the development of condensed matter physics and material preparation technology, carbon nanotubes, graphene, topological insulators and other materials have been successfully used 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, by theoretically calculating the relationship among gain, loss, dispersion and nonlinearity of the fiber laser in the Ginzburg-Landau equation, the dynamic mechanism of the formation of dark soliton pulses is theoretically analyzed, and the signal to noise ratio is obtained. Up to 94 dB results, the darkest soliton pulse output of the widest spectrum was experimentally 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 a newly published issue of "Nanoscale" (2017, 9: 5806) and were selected by the magazine as Highlights as the Inside front cover paper (as shown in Figure 1). The first author of the paper was Liu Wenjun. Ph.D., Correspondence author is Professor Lei Ming of Beijing University of Posts and Telecommunications and Wei Zhiyi, a researcher in the research group of the Institute of Physics, Chinese Academy of Sciences.

The study was supported by the Ministry of Science and Technology's 973 project and the National Natural Science Foundation of China (Grant Nos. 11674036, 11078022, and 61177040).

(Title: New Advances in the Research of Two-dimensional Nanomaterial Clamped All-fiber Lasers)