Carr C W, Radousky H B, Demos S G
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94551, USA.
Phys Rev Lett. 2003 Sep 19;91(12):127402. doi: 10.1103/PhysRevLett.91.127402.
A novel experimental approach is employed to understand the mechanisms of laser induced damage. Using an OPO (optical parametric oscillator) laser, we have measured the damage thresholds of deuterated potassium dihydrogen phosphate (DKDP) from the near ultraviolet into the visible. Distinct steps, whose width is of the order of k(B)T, are observed in the damage threshold at photon energies associated with the number of photons (3-->2 or 4-->3) needed to promote a ground state electron across the energy gap. The wavelength dependence of the damage threshold suggests that a primary mechanism for damage initiation in DKDP is a multiphoton process in which the order is reduced through excited defect state absorption.
采用一种新颖的实验方法来理解激光诱导损伤的机制。利用光学参量振荡器（OPO）激光器，我们测量了氘代磷酸二氢钾（DKDP）从近紫外到可见光范围内的损伤阈值。在与将基态电子激发越过能隙所需的光子数（3→2或4→3）相关的光子能量处，观察到损伤阈值存在明显的台阶，其宽度约为玻尔兹曼常数乘以温度（k(B)T）。损伤阈值的波长依赖性表明，DKDP中损伤起始的主要机制是一个多光子过程，其中通过激发缺陷态吸收降低了光子数的阶数。
