Dynamic behavior modeling of laser-induced damage initiated by surface defects on KDP crystals under nanosecond laser irradiation

Hao Yang,Linjie Zhao,Mingjun Chen,Jian Cheng,Qi Liu,Zhichao Liu,Jian Wang

doi:10.1038/s41598-019-57300-2

Hao Yang, Linjie Zhao + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-57300-2

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Abstract

The issue of laser-induced damage of transparent dielectric optics has severely limited the development of high-power laser systems. Exploring the transient dynamic behaviors of laser damage on KDP surface by developing multi-physics coupling dynamics model is an important way to reveal the mechanism of nanosecond laser damage. In this work, KDP crystals are taken as an example to explore the mechanism of laser-induced surface damage. Based on the theories of electromagnetic field, heat conduction and fluid dynamics, a multi-physics coupling dynamics model is established for describing the evolution of nanosecond damage processes. The dynamics of laser energy transmission, thermal field distribution and damage morphology during nanosecond laser irradiation are simulated with this model. It is found that the enhancement of light intensity caused by surface defect plays an important role in the initial energy deposition and damage initiation of the laser irradiation area. The evolution of temperature field and crater morphology during subsequent laser irradiation is helpful to understand the laser damage process. The feasibility of this model is verified by the morphology information of typical defect-induced laser damage. This work provides further insights in explaining the laser-induced damage by surface defects on KDP crystals. The model can be also applied to investigate the laser damage mechanisms of other transparent dielectric optics.

Highlights

The issue of laser-induced damage of transparent dielectric optics has severely limited the development of high-power laser systems
The results suggested that the hydrodynamic instability at the unstable phase-changing interface between the two phases in the damage region played a major role in generating the cracks in the solid optics of high stress
This section firstly shows the calculation of light field, thermal field and crater morphology during the nanosecond laser irradiation

Summary

Introduction

The issue of laser-induced damage of transparent dielectric optics has severely limited the development of high-power laser systems. Based on the light intensity distribution E(x, y) near the lateral crack on the front KDP surface, the temperature of the hot spot solved by the electromagnetic field model is assumed to be 9000 K at a the initial time due to the breakdown effect.

Results

Conclusion