Influence Of Air Heat Transfer Coefficient On Microchip Laser Thermal Effect

The miniaturization and highly integrated of solid state laser is one of the fastest growing direction of microchip laser at present. For the advantages of small size crystal, long operation time and high output power, the solid state laser have had some breakthroughs with the emergence of the microchip laser. These numerous advantages of microchip determine its broad applicable prospect in industry, medical, national defence and so on. Furthermore, microchip laser is cheap and easy to obtain mass production from the economic terms.However, the thermal effects of microchip would increase significantly along with the increase of pump power. The nonstable temperature gradient would been produced due to the transformation of part of the pumping energy into heat energy, which was absorbed by microchip laser crystal. Thus, thermal distortion in the end face of pumped and thermally induced birefringence occurred. All these would influence the quality of output light by microchip laser and output power.The tedious calculation of temperature field model with adiabatic end faces was improved by using Bessel functions and the property of solution for the standard Bessel's equation, which made the calculation much easier. The exact solutions of Poisson's equation were gained through Dini series and Bessel functions under the third non-homogeneous boundary conditions for the first time. Two models of adiabatic end faces and cooling end faces were compared and analyzed. The heat exchanger between the crystal and air must be considered when laser crystal was forced cold. Finally, a systematic study on the heat exchange between the crystal and the air was done, the results showed that laser crystal and the surrounding air could be considered adiabatic on general refrigeration, but the crystal and the surrounding air must be considered when laser crystal was forced cold.The conclusion and method of solving the temperature field provided a more comprehensive theoretical research base for the accurately analyzing the thermal effects of microchip.