Studies On Output Performance Of High-energy Ho:YAG Solid-State Laser

2μm laser is eye-safe wavelength which at the atmospheric transmission window.And water have a great absorption efficiency on2μm laser.2μm laser can be also beused as3¹2μm tunable infrared laser pump sources. This series of advantages make2μm laser has many applications in military, medical, commercial, scientific researchand so on. Now2μm laser has become the research object around the world. The solid-state laser that single crystals Ho³⁺doped has more advantages than other programs. It’seasier to obtain high power, high energy and good beam quality2μm laser. In order toobtain high energy and good beam quality2μm laser, this article is mainly based onHo:YAG solid-state laser as research object. And the article has made a research onoutput of the laser from theoretical and experimental.In the aspect of theory, based on Ho:YAG crystals’ absorption and emissionspectrum, output wavelength and pump wavelength of Ho:YAG laser have beenanalyzed from the standpoint of gain cross section. The thermal distribution of crystaland thermal lens effects have been analyzed based on the constructed virgulate crystalthermal model. And the expression of thermal focal length has achieved from the modeltoo. According to the transition mechanism of Ho ion, the quasi two-energy-level rateequation model has been established. Using this model, the influences of laser crystal,pump source and laser resonator on the laser output performance are numericallycalculated and discussed. The Ho:YAG laser resonator is studied, and designed twokinds of different type cavity. The conditions which influence the stability of cavity andoscillation light spot size in the cavity have analyzed theoretically.In the aspect of experiment, based on the previous work, the room temperatureoperation of Ho:YAG laser experiments on two different kinds of cavity were carriedout. First, in the “L” type cavity, Ho:YAG crystal size is Φ5×45mm3, and Ho ion dopingconcentration is0.8at.%. The Ho:YAG oscillation cavity obtained maximum outputpower of32.9W under93.9W incident pump power. And the slope efficiency andoptical-to-optical conversion efficiency of52.26%and35%respectively. Under Q-switch,1kHz pulse repetition rate, the maximum output energy and pulse width of30mJand28.2ns respectively was obtained. After primary amplifier, the Ho:YAG laser hasobtained maximum continuous output power and pulse output energy of55.2W and52mJ. The wavelength of Ho:YAG laser is2090.6nm and beam quality factor M2is2.1.Second, in the “M” type cavity, Ho:YAG crystal size is Φ5×50mm3, and Ho ion dopingconcentration is0.5at.%. Under Q-switch,100Hz pulse repetition rate, the maximumoutput energy and pulse width of52.51mJ and35ns respectively was obtained withincident pump power of75.6W. The wavelength of Ho:YAG laser is2090.7nm and beam quality factor M2is1.16.