Optimization of morphological parameters for mitigation pits on rear KDP surface: experiments and numerical modeling

Hao Yang, Jian Cheng, Mingjun Chen*, Jian Wang, Zhichao Liu, Chenhui An, Yi Zheng, Kehui Hu, Qi Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)
11 Downloads (Pure)

Abstract

In high power laser systems, precision micro-machining is an effective method to mitigate the laser-induced surface damage growth on potassium dihydrogen phosphate (KDP) crystal. Repaired surfaces with smooth spherical and Gaussian contours can alleviate the light field modulation caused by damage site. To obtain the optimal repairing structure parameters, finite element method (FEM) models for simulating the light intensification caused by the mitigation pits on rear KDP surface were established. The light intensity modulation of these repairing profiles was compared by changing the structure parameters. The results indicate the modulation is mainly caused by the mutual interference between the reflected and incident lights on the rear surface. Owing to the total reflection, the light intensity enhancement factors (LIEFs) of the spherical and Gaussian mitigation pits sharply increase when the width-depth ratios are near 5.28 and 3.88, respectively. To achieve the optimal mitigation effect, the width-depth ratios greater than 5.3 and 4.3 should be applied to the spherical and Gaussian repaired contours. Particularly, for the cases of width-depth ratios greater than 5.3, the spherical repaired contour is preferred to achieve lower light intensification. The laser damage test shows that when the width-depth ratios are larger than 5.3, the spherical repaired contour presents higher laser damage resistance than that of Gaussian repaired contour, which agrees well with the simulation results.

Original languageEnglish
Pages (from-to)18332-18345
Number of pages14
JournalOptics Express
Volume25
Issue number15
DOIs
Publication statusPublished - 20 Jul 2017
Externally publishedYes

Keywords

  • high power laser systems
  • precision micro-machining
  • mitigation pits
  • otassium dihydrogen phosphate (KDP)
  • surface repair
  • finite element method (FEM)
  • optimization
  • morphological parameters
  • experiments
  • numerical modelling

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