基于边界对流传热的LD端面抽运圆柱形晶体的热效应

Thermal Effect of LD End-Pumped Laser Crystal Rods Based on Convective Heat-Transfer about Side Surface

通过对激光二极管(LD)端面抽运棒状Nd:YAG晶体的热效应进行理论分析,考虑晶体内部抽运光束分布及连续抽运过程中晶体周边与冷却液之间的对流传热,建立了更为合理的边界条件,得出更符合实际的晶体温度分布场,同时计算了晶体半径以及晶体散热面积对热效应的影响。研究结果表明,考虑边界对流传热后,计算的晶体中心温度升高,晶体边界温度也相应升高,相应的晶体热焦距稍有增加;减小晶体半径,晶体中心与表面的温度差均减小,热焦距增大,晶体热效应降低;增大晶体散热面积虽然降低晶体内部温度场,但由于端面抽运的特点导致晶体中心附近温度变化率增加,反而使热焦距减小,加剧了晶体热效应。

The thermal effect of Nd： YAG crystal rods induced by laser diode-pumped is analyzed theoretically, the more rational boundary conditions are established considering the distribution of laser beam in the crystal and the heat convection between the side surface of the crystal and the coolant. As a result, the more actual temperature field in the crystal is obtained, and the influences of crystal radius and side surface area on thermal effect are calculated simultaneously. The results show that the temperature in the center and on the side surface of the crystal increases when the convective heat-transfer about the side surface is considered, the focal length of crystal increase a little bit correspondingly. As decreasing the crystal radius, the differences in temperature between the center and the side surface of the crystal decrease, the focal length of crystal increases and the thermal effect of the crystal reduces. As increasing the side surface area, the temperature of the crystal decreases, while the focal length of crystal decreases and the thermal effect aggravates, for the rate change of temperature nearby the crystal center increases for the feature of end-pumped.