Observation and optimization of 2 μm mode-locked pulses in all-fiber net anomalous dispersion laser cavity
With the rapid development of laser technology and optoelectronic devices, 2 μm band laser has been widely used in the fields of mid-infrared source generation, biomedics, optical communication, LiDARs, etc., and it is one of the most promising and emerging laser technologies. At present, in the all-fiber laser cavity, using mode-locked technology to achieve ultra-short pulse output has the advantages of good stability, high efficiency, high integration and strong anti-interference ability. Especially at 1 μm and 1.5 μm band, the output power, pulse width, pulse energy, peak power and other indexes of mode-locked fiber laser have been fully improved. Femtosecond mode-locked fiber laser has started to enter the stage of industrial application with a large number of practical mode-locked fiber laser products on the market. When compared with 1 μm and 1.5 μm band, the output performances of mode-locked fiber laser at 2 μm band does not reach the level of 1 μm and 1.5 μm band due to the high cost of fiber devices, the large loss of pulse transmission in single-mode fiber, the lack of dispersion compensation mechanism, and the relatively difficult design of mode-locked structure. In particular, the pulse energy and pulse width of the mode-locked fiber laser are much lower than those of the other two bands. Therefore, it is important and meaningful to realize ultra-short pulses at 2 μm band with high energy, narrow pulse width, high repetition rate and high stability in all-fiber laser.
Fig.1 2 μm all-fiber mode-locked laser struc-ture
In order to solve the above problems, the generation and output performance optimization of a variety of 2 μm high energy mode-locked ultra-short pulses in an all fiber resonator are demonstrated in this paper. The generation and optimization of 2 μm conventional soliton, stretched pulse and noise-like pulse based on commercial ultra-high numerical aperture fiber are fully discussed. Hundred femtoseconds pulse width, several nJ pulse energy level ultra-short pulse can be directly generated in 2 μm band. On this basis, an all-fiber like-chirped-pulse-amplification structure is proposed, which is suitable for accurate pulse width measurement of 2 μ m ultrashort pulse. The related research can provide more reliable high energy ultra-short pulse source for further analysis of dynamic characteristics, intelligent control, spatial information transmission, all-optical high-speed signal processing and other fields of 2 μm mode-locked fiber lasers. It can also provide important technological reference for further system integration of 2 μ m ultra-fast fiber lasers. Based on the research content of this paper, the research group has made a preliminary breakthrough in high-speed spatial optical communication and all-optical signal processing technology based on 2 μ m mode-locked fiber laser. More following-up reports on this research can be expected. This work is supported by NSFC, the first author is Dr. Wanzhuo Ma, a young lecturer of the research group, and the corresponding author is Professor Tianshu Wang.
About The Group
Professor Tianshu Wang and Dr. Wanzhuo Ma’s research group from Changchun University of Science and Technology has long been engaged in research on the transmission characteristics of fiber lasers and free-space data transmission. The research group undertakes a number of scientific and technological projects at the national and provincial levels such as the Military Commission and the National Natural Fund. More than 60 papers have been published in important optical journals such as Optics Letters，Optics Express，IEEE Journal of Selected Topics in Quantum Electronics，IEEE Photonics Technology Letters and Applied Optics. The research group has more than 20 national patents for invention, and won the first prize for technological invention in Jilin province in 2018. The research results "2μm wideband tunable fiber laser" were evaluated by the third-party achievement evaluation organization to obtain " domestic leading, international advanced "evaluation. A series of breakthroughs have been made in the field of 2 μm ultrafast fiber laser for all-fiber femtosecond laser generation, high energy mode-locked pulse generation and high repetition rate mode-locked pulse generation. The study of propagation characteristics of partially coherent beams in turbulent channel has been studied. On this basis, the research group broke through the study of propagation characteristics of 2 μm mode-locked fiber laser, and obtained a lot of research results.
Ma W Z, Zhao D S, Liu R M, Wang T S, Yuan Q et al. Observation and optimization of 2 μm mode-locked pulses in all-fiber net anomalous dispersion laser cavity. Opto-Electron Adv 3, 200001 (2020).