The Measure And Calculate With The Thermal Effect Of Laser Crystal

Diode-pumped solid-state laser is widely used in national defence, military, basic research, communication, material processing, medical therapeutics and sanitation, photoelectron industry etc. It has lots of advantages, such as high efficiency, long lifetime, stability, compactness and all solid-state construction. So, it has become the researching emphasis because unique merits. In the design of laser diode end-pumped all-solid state lasers,a temperature gradient is formed in the laser crystal and as a result of the absorption of the pump power, the temperature at the center of the laser crystal is higher than the edge, so a deformation of the surface appeared and a thin convex was formed. Moreover, the change of refractive index of the laser crystal devotes to the thermal lens effect and makes the designing of the laser cavity more difficult. The matter of hindering scaling of diode-pumped solid-state lasers is heat deposition within the laser medium. The thermal conduct model of laser crystal was established.Using Possion equation, the temperature distributionin, the OPD and focal length in Yb:YAG crystal were obstained with different Yb ions concentration. Based on the former calculation, we obtained the temperature distribution of end-face with different pumping radius. The study shows that in the same condition, when the Yb ions concentration increase, the central temperature of Yb:YAG crystal's pumped face will rise and the temperature of crystal central axis will reduce-faster,and the focal length will lower.When the pumping radius increase,the central temperature of Yb:YAG crystal will reduce.As the laser crystal type of broad, the calculation of thermal effect of the process is relatively complicated to calculate thermal effects of the procedures and methods is very mixed, that has been no uniform requirements or rules.In the calculation, users of the research process will inevitably cause unnecessary distress, wasting valuable time and energy, greatly reduces the efficiency of scientific research. And the calculation did not take into account the past and cooling liquid crystal between the subordinate of the convective heat, which greatly affect the accuracy of the calculation for the stability of the laser is very negative. Here, we will be more fully into account the factors that affect the crystal thermal effects, and use the computer to build a mixed language interface in the form of specialized measurement systems thermal effect of laser crystals, laser crystals for the use and scientific research to provide a more comprehensive measurement system.The contents can be outlined as follows:1. Reviewed the history and progress of diode-pumped solid-state lasers; and analysed the characters of the diode-end-pumped solid-state laser; then presented the cause of engendering and the harmful effect of laser crystal.2. On the basis of the thermal effect theory of laser crystal. By using this theory, the thermal conduct model of laser crystal was established. Some considerations of useful methods were presented. And then found the difference elements of elimination and inhibition.3. The rectangle thermal conduct model of Yb:YAG laser crystal was established. Using Possion equation,the temperature distribution, the OPD and the thermal focal length in Yb:YAG laser crystal were obstained with different Yd ions concentration, and the temperature of pumped face distribution was obtained with different pumping radius. When the pumping power is 10W, the radius of pumping beam is 320μm, and the Yd ions concentration separately were 5at%, 10at%, 20at%, the central temperature of Yb:YAG crystral is 67.7℃,147.8℃,247.7℃. we obtained that , when the Yb ions concentration increase, the end-pumped central temperature of Yb:YAG crystal's was higher, the thermal effect was aggravating. When the radius of pumping beam are 200μm, 320μm, 400μm, the central temperature of end-pump is 174.6℃,147.8℃and 134.9℃. When the pumping radius reduce, the central temperature of Yb:YAG crystal will higher. The conclusion will give a theoretical direction for improving the thermal effect of Yb:YAG crystal.4. Using the computer being enrolled together language, the computation thermal reaction matlab procedure association which will complete is, forms an over all software, by contact surface input parameter form, fast convenient completion to different crystal thermal reaction computation and output.