Temperature Field Analysis Of Pulse LD End-pumped Nd:YAG Crystal And Composite Nd:YAG

Diode laser pumped solid state laser (DPSSL) with high efficiency, small volumeand high beam quality has wide applications in many fields, such as industry,communication, defense, medical treatment and scientific research. With thedevelopment of high power diode lasers, high power DPSSL has become one of themain objectives of research in the laser field. The researches of DPSSL have mainlyconcentrated on improving output power, while a high beam quality remains. However,the key obstacle of these problems is thermal deposition in the laser medium. Lasercrystal is one of the core part of DPSSL, the theral effect of laser crystal has alwaysbeen one of hot issues. Among all kinds of laser gain mediums, Nd-ions doped lasercrystals, which have large stimulate-demission cross section at lasing wavelength, highabsorption of pump radiation in a small crystal region and good physical and chemicalproperties, have been often used in DPSSL. Especially in recent years diode laserpumped Nd3+lasers have got considerable progress.In this paper, the introduction of development and current situation of the DPSSLwas given. This paper analyses the facts of thermal effect, and provid a bunch ofmeasures to cure the heat deposition.The contents can be outlined as follows:1. Established the end-pumped the rectangular Nd:YAG and Nd:YAG rod solidstate laser thermal model. The more actual temperature field in the crystal is obtainedvia constant transform method and secant method, considering the thermal conductivity of Nd:YAG with a function of temperature. The secant method is able to reduce nearly40%calculation amount, while the definition remains.Then the internal temperaturefield distribution was calculated under different super-Gaussian beam orders and pumpspot sizes.2. Based on the analysis of pulse end-pumped Nd:YAG rod, composite Nd:YAGstate laser thermal model is established. The length of YAG is taken into account in theinternal temperature field distribution.3. Based on the theoretical formulas, the temperature changing rules are simulatedwith the three types of crystals in non-steady-state stage and quasi-thermal-equilibriumstage by Mathematica sofeware. Compared the data with that in former publishedpapers, the results have been proved. The research methods and results can also be usedto analyze other time-varying thermal problems in laser systems, and will play adirectional role in solving thermal problems in laser systems.