采用高速PIN光电探测器和高带宽的数字存储示波器,实时检测透射光脉冲和散射光脉冲的变化特征,并将之用作材料破坏的光学判据,测量得到K9玻璃在1.06μm纳秒脉冲激光作用下的能量损伤阈值约18mJ,相应的能量密度阈值为1.0kJ/cm².通过分析透射光脉冲和散射光脉冲的特征,给出了材料的破坏时刻,并推断出K9玻璃所能承受的极限光强为10¹⁵W/m².研究了能量透过率与泵浦能量的关系,并初步探讨了透明材料的破坏机理.结果表明:在多纵模激光的作用下,透明光学材料破坏是电离击穿与自聚焦效应综合作用的结果.

Experiment system to measure the damage thresholds of K9 glass irradiated by ns pulsed laser is established. Strong attention is paid to the method to detect the precusor of the damage. The sharp decrease of transmissivity or generation of scattered light are assumed to be the damage precursor, and thereby damage threshold is measured to be 18mJ or 10¹⁵W/m², and the dependence of transmissivity on incident energy is presented. From the experiment result, it is found that avalanche ionization and self-focusing effect dominate the damage process in transparent dielectric.