Research On Tm:LuYAG Laser Pumped By Pulsed Laser Diode

Thulium-doped all-solid-state laser pumped by laser diode is an important way to realize 2μm band laser.It has stable performance,long service life,small size,light weight,high efficiency,and large market demand are indispensable in many fields.Such as laser medical treatment,laser processing,information industry,laser weapons and tactical equipment,etc.As the continuous development and research of 2μm lasers,how to efficiently improve the laser output quality of all-solid-state lasers has become a research hot topic for scholars at domestic and international scholars.However,the thermal effect of laser medium is the primary obstacle to obtain high-quality laser output.According to the research,we can see that the pulse LD pump is very effective in alleviating the thermal effect of laser working materials.In this paper,a novel pulsed LD end-pumped Tm:LuYAG laser is studied from theoretically and experimentally.Main research contents:Theoretically,based on the analysis of Tm: LuYAG crystal properties,select the appropriate pumping source according to its absorption spectrum characteristics.By analyzing the energy level structure and transition process of Tm3+ in Tm: LuYAG crystal,the rate equation of pulsed LD end-pumped Tm: LuYAG laser is established.And the output characteristics of Tm: LuYAG laser are calculated based on the theory.On the basis of heat conduction theory,a thermal model of the new Tm: LuYAG crystal is established.Solving the transient heat conduction equation combined with pulsed LD end-pumped boundary conditions of Tm: LuYAG crystal.And then the expression of transient temperature distribution in the crystal rod is obtained.Then,the transient thermal effect of pulsed laser diode single-end pumped Tm: LuYAG laser was simulated,analyzed and discussed under different spot radius,pump power,duty ratio and pulse width.The expression of the time-varying thermal focal length of the crystal rod is obtained by the thermal path difference caused by the temperature gradient,the thermal focal length of Tm:LuYAG crystal was simulated under different pumping conditions.Design a suitable resonant cavity considering the thermal focal length to provide theoretical basis for the experiment.Experimentally,we set up the experimental platform of pulsed LD end-pumped Tm :LuYAG laser.Realized the output characteristics of pulsed LD end-pumped Tm: LuYAG laser at different repetition frequency,duty ratios and different pump modes.When the repetition frequency of pulse pump is 10 Hz,100 Hz and 1000 Hz,and the duty cycle is50%,the maximum output energy of Tm: LuYAG laser of 724 m J,70 m J and 6.36 m J is obtained.In addition,under the pump condition of repetition rate is 10 Hz and duty cycle is75%,the maximum output energy of 900 m J is obtained,and at this time slope efficiency is34.6%.Tm: LuYAG laser output center wavelength is at 2018.96 nm and the beam quality is Mx2 = 1.96,My2 = 1.98.It can be seen from the experimental results that the pulse pump technology can effectively alleviate the serious thermal effect of all-solid-state lasers.So as to improve the feasibility of its laser output characteristics.