The relationship between the laser damaged threshold and step velocity in different supersaturation regions

The laser damaged threshold (LDT) of potassium dihydrogen phosphate (KDP) crystals grown at different supersaturation points were investigated using a Nd:YAG nanosecond laser. The growth rate was measured by a laser polarization interference system. Combining the step slopes, the dependence of v-(σ) was obtained. It is interesting that the dependence of LDT-(σ) can also be divided into three areas and shows a similar dependence to that of v-(σ). The LDT reduces rapidly at the transition supersaturation area, and has the lowest value at σ = 0.07. In different supersaturation regions, the micro morphology of the KDP crystals was observed using an atomic force microscope. The nature of the step movement and bunching together of steps may contribute to the dependence of LDT-(σ).