Single-frequency fiber laser research has made important progress

Recently, Prof. Mao Qinghe, Anhui Institute of Optics and Mechanisms, Chinese Academy of Sciences, made a significant progress in single-frequency fiber laser research. A Q-switched fiber laser was designed and developed based on the seed injection technology and the ring cavity. Modulated laser pulse output, direct output Q-switched laser pulse width narrow to 1.5 MHz, is currently the world's narrowest linewidth Q-switched fiber laser pulse, and the repetition rate of 1 ~ 100 kHz, pulse width of 50 ~ 400ns adjustable. Relevant achievements have been published in the IEEE Photonics Journal (2017, 9 (1), 1500607). In order to obtain this very narrow linewidth pulse laser, the group has been for many years efforts. First, a single-mode low-noise continuous-wave fiber laser with linewidth less than 10 kHz was designed and developed. The relative intensity noise and frequency noise of this laser are -110dB / Hz and 45dB Hz2 / Hz, respectively. Furthermore, Based on the low-pressure gas cavity frequency reference of the hollow-core photonic crystal fiber (HC-PCF), the frequency stabilization of continuous-wave fiber lasers is realized, which solves the problem of seed laser source injected into the single-longitudinal mode Q-switched fiber lasers. On this basis, by eliminating such adverse effects as the pigtail acousto-optic modulator producing frequency shift in the single-mode Q-switched laser operation of seed injection, an Q-switch of active intensity modulation is finally obtained to obtain extremely narrow linewidth Single longitudinal mode Q-switched fiber laser pulse. At present, the group also uses optical fiber amplification technology, this single longitudinal mode Q-pulse energy has been raised to 0.2mJ, line width is still less than 2MHz, while for continuous-wave fiber laser, the power is increased to 10W, the line width is still Keep within 40kHz. In addition, this kind of high-power single-longitudinal-mode CW and pulsed fiber laser has been developed into an engineering prototype by reasonably designing a cooling system and a pump control module. Preliminary applications have been obtained. These developments are also published in IEEE Photonics Technology Letters, Applied Optics and other journals in recent years. The single longitudinal mode CW or pulsed laser light source has broad application prospects in the fields of material fine structure analysis, precision laser spectroscopy and high-end laser radar, gravitational wave detection and coherent detection and sensing. The research work was supported by the National High-tech Research and Development Program, the National Natural Science Foundation of China, and the Strategic Pilot Science and Technology Project (Class B) of the Chinese Academy of Sciences. Single longitudinal mode Q fiber laser structure diagram Single longitudinal mode characteristics and linewidth of Q-switched fiber laser pulse DBR single longitudinal mode fiber laser prototype High power single longitudinal mode fiber laser prototype