A Study On LD End-pumped 2μm Band High-power Solid State Laser

Lasers working in the 2μm eye-safe wavelength region have important applications in medical operation,military and material processing fields due to the low absorption in atmosphere and the strong absorption of water.Solid-state lasers stand out in many lasers because of its compact structure,large output power and strong adaptability.Rare earth ion doping with Tm or Ho is an important approach to obtain 2μm band laser output.So in this dissertation,lasing characteristics of high power and high beam quality Tm:YAG slab laser at 2μm band are investigated.And due to the lack of high power LD pump source as that commercially and economicaly available for Tm-doped laser,spectral properties and laser performance of Tm,Ho:YAG ceramic laser are also investigated.The main contents are as follows:1.A high-power Tm:YAG crystal slab laser system has been designed and built.State-of-the-art micro-channel cooling technology was adopted and the dynamic stress compensation mechanism was introduced for effective thermal management.We built a waveguide homogenization system for the LD pump source and optimized the parameters of the laser.At 350 W of incident pump power,over 100 W of output power at～2015 nm has been generated.The laser had a threshold of 46.7 W,corresponding to an optical-to-optical conversion efficiency of 28.6%,and the slope efficiency is33.6%.2.On the basis of hundred-watts-level high Power Tm:YAG slab laser,using Innoslab configuration we demonstrated the feasibility of achieving the high power and high beam quality output in the 2μm band.At 184 W of incident pump power,a maximum output power of 36.4 W was achieved,corresponding to a slope efficiency of 23.4%.The beam quality factors M~2 were measured to be 1.23 in the unstable direction and 1.44 in the stable direction.3.Absorption and fluorescence spectrum of the home made Tm,Ho:YAG ceramic sample were measured and analyzed.And later the laser experiment was carried out,we analyzed the influence of resonator design,doping concentration of the ceramic material and the transmittance of the output mirror on the output characteristics of the laser.A maximum output power of~1.2 W with a slope efficiency of 16.7%has been generated from the 3at.%Tm,0.5at.%Ho:YAG ceramic.And the beam quality factor M~2 was measured to be~1.19 in the two directions.This Tm,Ho:YAG ceramic laser operated at either dual-wavelength or even three-wavelength,and the central wavelength were around 2090 and 2096 nm.Besides,with the increase in the absorbed pump power and the output coupler transmittance,blue-shift of the emission wavelength was observed.