Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also provide a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.
Elhadj, S., et al. "Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating." Applied Optics, vol. 56, no. 8, Mar. 2017. https://doi.org/10.1364/AO.56.002217
Elhadj, S., Steele, W. A., VanBlarcom, D. S., Hawley, R. A., Schaffers, K. I., & Geraghty, P. (2017). Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating. Applied Optics, 56(8). https://doi.org/10.1364/AO.56.002217
Elhadj, S., Steele, W. A., VanBlarcom, D. S., et al., "Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating," Applied Optics 56, no. 8 (2017), https://doi.org/10.1364/AO.56.002217
@article{osti_1366904,
author = {Elhadj, S. and Steele, W. A. and VanBlarcom, D. S. and Hawley, R. A. and Schaffers, K. I. and Geraghty, P.},
title = {Scalable process for mitigation of laser-damaged potassium dihydrogen phosphate crystal optic surfaces with removal of damaged antireflective coating},
annote = {Here, we investigate an approach for the recycling of laser-damaged large-aperture deuterated potassium dihydrogen phosphate (DKDP) crystals used for optical switching (KDP) and for frequency conversion (DKDP) in megajoule-class high-power laser systems. The approach consists of micromachining the surface laser damage sites (mitigation), combined with multiple soaks and ultrasonication steps in a coating solvent to remove, synergistically, both the highly adherent machining debris and the laser-damage-affected antireflection coating. We then identify features of the laser-damage-affected coating, such as the “solvent-persistent” coating and the “burned-in” coating, that are difficult to remove by conventional approaches without damaging the surface. We also provide a solution to the erosion problem identified in this work when colloidal coatings are processed during ultrasonication. Finally, we provide a proof of principle of the approach by testing the full process that includes laser damage mitigation of DKDP test parts, coat stripping, reapplication of a new antireflective coat, and a laser damage test demonstrating performance up to at least 12 J/cm2 at UV wavelengths, which is well above current requirements. Our approach ultimately provides a potential path to a scalable recycling loop for the management of optics in large, high-power laser systems that can reduce cost and extend lifetime of highly valuable and difficult to grow large DKDP crystals.},
doi = {10.1364/AO.56.002217},
url = {https://www.osti.gov/biblio/1366904},
journal = {Applied Optics},
issn = {ISSN 0003-6935},
number = {8},
volume = {56},
place = {United States},
publisher = {Optical Society of America (OSA)},
year = {2017},
month = {03}}