Mid-infrared all-fiber gain-switched pulsed laser at 3 μm

Fiber lasers have got extensive attention due to their inherent merits of compactness, good system stability, reduced thermal effects, low operating cost and excellent beam quality. There is no space coupler in the resonator of all-fiber laser, which is easier to adjust and integrate, and can effectively reduce the sensitivity to external noise. In recent years, the mid-infrared laser operating at a waveband from 3 μm to 5 μm has become one of the research hotspots at home and abroad due to its huge potential advantages. In addition, the mid-infrared pulse laser has a broad application prospects in the fields of material processing and optical communication due to its good performance such as higher peak power and higher energy. In general, microsecond and nanosecond grade pulsed lasers are obtained by Q-switching or gain-switching technology. Different from Q-switching technology, the gain-switching technology does not need to insert a modulator or saturable absorber in the cavity, but only needs a pulsed pump source to pump a gain fiber to achieve the desired laser pulse output.

According to the shortcomings of current mid-infrared fiber laser source, which is difficult to be all fiberized and needs high manufacturing cost, the research group of Prof. Luo Zhengqian from Xiamen University proposes a method of establishing all-fiber laser cavity. They use the fiber end coated mirror instead of the traditional bulk input-output coupling device to realize the input coupling of the pump light and the output coupling of the laser signal, so as to ensure the all fiber structure of the laser. The nanosecond grade pulsed laser output is achieved by using the gain switching technology, i.e. a 1.15 μm pulsed pump source to pump holmium doped fluoride fiber. At the same time, the effects of gain fiber length, average pump power, pump repetition rate, output coupling and other factors on the output performance of the gain-switched fiber laser are discussed in detail. This work has important reference value for how to use the gain switch technology to obtain the output pulse laser with narrower pulse width, higher repetition rate and higher pulse energy in the future, and provides a new method for the realization of all fiber mid-infrared gain-switched pulsed laser.

(a) The experiment device diagram of the compact 3 μm gain-switched laser with an all-fiberized structure; Inset: actual photo of the fiber end-facet mirror M. (b) Measured transmission optical spectrum of the M.

About The Group

The research group of Prof. Luo Zhengqian from Xiamen University has 4 doctoral students and 10 postgraduate students. At present, the research group mainly work in laser physics, on-chip photonics and nonlinear fiber optics, and has published more than 110 international journals and conference papers. Since 2015, their papers have been cited for more than 2870 times. Prof. Luo received the Science Funds for Distinguished Young Scientists of Fujian Province Young Top Notch, Talents of Fujian Province, and the Program for New Century Excellent Talents in Fujian Province, China. He has been committed to the research of new fiber laser technology for more than ten years. Aiming at the development of high-performance miniaturized pulsed fiber laser, he has made a number of important research progress, presided over three national projects in the field of optical fiber pulsed laser, three provincial and ministerial projects, and other 5 projects entrusted by enterprises and institutions.

Article

 Zhang X J, Li W W, Li J, Xu H Y, Cai Z P et al. Mid-infrared all-fiber gain-switched pulsed laser at 3 μm. Opto-Electron Adv 3, 190032 (2020).

DOI:10.29026/oea.2020.190032