Enhanced uniformity of zirconia coating for high power lasers via solvent replacement and PEG-doping

Zirconia coating has a lot of promise when it comes to enhancing the optical performance and laser-induced damage threshold (LIDT) of the mirror in laser systems. In this work, a high LIDT ZrO₂ coating was created using the sol-gel spin coating technique. The anhydrous ethanol solvent was substituted with alcohol ether solvent, and the spin coating technique was employed to achieve a macro homogeneous and flawless ZrO₂ coating. Additionally, organic polymer polyethylene glycol (average Mn 200, PEG200) doping was used to achieve the uniform ZrO₂ coating with LIDT. ZrO₂-PEG composite coatings with consistent LIDT and exceptional optical properties were created. Alcohol ether solvents helped the sol produce a more homogeneous gel coating on the substrate, as demonstrated by the ZrO₂ coating microscope pictures. The LIDT with a 0.5 wt.% PEG200 content was the most uniform. PEG200 organic molecules were able to alter the link state of the ZrO₂ particles. The macroscopic mechanical characteristics of the coatings revealed that the hardness and elastic modulus of the ZrO₂-PEG composite coating were mostly influenced by the PEG200 content. When the PEG200 content was 0.3 wt.%, the hardness and elastic modulus of the ZrO₂-PEG composite coating were the lowest with the highest of the LIDT at 39.25 ± 3.13 J/cm² (@ 1064 nm, 11 ns, 1 mm²).

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