Study Of High-power LD End-pumped Water-cooled Rotary Nd:YAG Laser

LD end-pumped solid-state lasers are widely used due to their compact structure and high efficiency.But the increase of output power is limited by the thermal effect.In this thesis,a new solid-state laser is proposed.In the case of water-cooling technology,the gain medium rotates around the optical axis of the resonator to reduce the thermal effect of the gain medium.In this thesis,a systematic study of LD end-pumped water-cooled rotary Nd:YAG laser is carried out.The main research contents and results of this thesis are as follows:(1)The resonator parameters and motion system of the laser are optimized.The MATLAB software is used to simulate and calculate the resonant cavity with different cavity types and cavity lengths,and a resonator scheme to match the pump beam and the fundamental mode beam is obtained on the premise of maintaining the stable cavity.The motion system is designed to realize the gain medium rotation and water cooling.For the core component rotating device in the motion system,a single bearing structure and a double bearing structure are proposed.(2)Through experimental research,when the pump power is 150W,the maximum output power of the laser is 62.6W,the optical-to-optical conversion efficiency is 41.7%,and the slope efficiency is 45.9%.The output power is limited by the maximum pump power available in the experiment.If the pump power is increased,a higher output power will be obtained.By measuring the temperature of the pump area of the gain medium,it is found that for every 1W of pump light absorbed,the temperature of the gain medium increases by about 0.114?.It shows that the water-cooled rotating laser has outstanding heat dissipation capability,can break through the limitation of the thermal effect of the end-pumped laser,and has the ability to achieve high-power laser output.(3)Analyze the quality of the laser beam by processing and analyzing the spot image.When the pump power is 40W,the output beam quality is better when the laser uses a dual-bearing rotating device with better stability,and the beam quality factors M~2in the horizontal and vertical directions are 1.53 and 1.61.When the laser uses a single-bearing rotating device,the output spot mode is unstable.It shows that the stability of the rotating device has an important influence on the output performance of the laser.Through the research of this thesis,it is found that the LD end-pumped water-cooled rotary Nd:YAG laser has outstanding heat dissipation capacity and has the ability to output high-power laser.It is significant to break through the power limit of LD end-pumped solid-state laser and promote the development of LD end-pumped solid-state laser.