885 nm直接抽运946 nm Nd∶YAG低温激光特性研究

Characteristics of Cryogenically Cooled 946 nm Nd∶YAG Laser Under 885 nm Direct Pumping

对低温下885nm抽运Nd∶YAG晶体946nm准三能级激光性能进行了研究。将激光上、下能级的玻尔兹曼分布分数f_1、f_2作为温度的函数引入到激光速率方程中,定性分析了低温下小信号增益和激光阈值的变化规律。利用搭建的低温冷却系统研究了不同晶体温度下946nm激光的输出性能,在210K时获得了最大165 mW的激光输出,斜效率为36%,相比于常温下斜效率提高了71%。观察并分析了低温下1061nm增益增强的现象,当温度低于190K时,1061nm激光增益显著提高,与946nm激光形成竞争,导致946nm激光输出降低。

The characteristics of cryogenically cooled 946 nm Nd∶YAG laser under 885 nm low quantum defect pumping are studied.The Boltzmann distribution fraction of the upper and lower laser levels as a function of temperature is introduced into the laser rate equation,and the change rule of small signal gain and laser threshold at low temperature is analyzed qualitatively.A cryogenic system is developed to study the output characteristics of the 946 nm laser at low temperature.A maximum 165 mW laser output with the slope efficiency 36% is achieved at 210 K.The slope efficiency is increased by 71% compared with the room temperature operation.The gain of 1061 nm laser enhanced at low temperature is observed and analyzed.When the temperature is lower than 190 K,the gain of 1061 nm laser significantly increases and 1061 nm laser competes with 946 nm laser,resulting in a decrease of 946 nm laser output.