Research On Erbium Doped ZBLAN Fiber Laser

The mid-infrared laser is located in the molecular fingerprint region so that it has a unique prospect in the field of spectral sensing.In addition,it also has important application in the field of medicine,material processing,national defense and military industry.Although there have been a variety of ways to generate mid-infrared laser,more and more researchers are attracted by mid-infrared fiber lasers because of their inherent advantages such as good beam quality,high conversion efficiency and good heat dissipation.In this paper,mid-infrared fiber laser based on the rare earth ion Er3+ doped ZBLAN fiber as the gain medium has been studied.This paper introduces the mechanism of 3.5 μm and 2.8 μm laser based on the energy level structure of Er3+.Towards 2.8 μm laser output,a wavelength tunable 2.8μm single longitudinal mode laser is achieved using FP compound cavity as the mode selecting mechanism.By tuning the angle of the diffraction grating,the center wavelength can be tuned from 2705 nm to 2806 nm with a tuned range of more than 100 nm.The power of the single longitudinal mode laser is up to 450 mW.We analyze theoretically the mechanism of the single longitudinal mode laser and design a comparison experiment to verify it.Towards 3.5 μm laser output,a theoretical study on the stark splitting energy level of Er3+ is carried out so that we are going to choose a wavelength tunable 2 μm laser as a substitute for a fixed 2 μm laser and a 976 nm laser as the dual-wavelength pump resource.The 2 μm high power wavelength tunable laser is set up and its power is amplified.The tuning range is from 1940 nm to 2040 nm.After primary optical amplification,the maximum output power of the 1976 nm was 6.2 W when the 793 nm pump power is increased to 15 W.The optical conversion efficiency reaches 41%.The amplified power of the 1960 nm-1990 nm laser is maintained around 6 W.