Cover Story：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). 

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. Zhengqian Luo 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 on how to use the gain switching 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.