Stress compensated anti-reflection coating for high power laser deposited with IBS SiO2 and ALD Al2O3

Abstract Both low stress and high laser induced damage threshold are required in the development of high power large laser facilities. IBS and ALD films have potential in such applications in aspects of film thickness control and high LIDT, but their severe stresses cause an obstacle towards the widely application. The origin of compressive stress of IBS coating and tensile stress of ALD coating is analyzed with a model based on intermolecular potential. An anti-reflection coating having compensated stress is designed and fabricated with ALD Al2O3 and IBS SiO2. The LIDT of the anti-reflection coating as well as the single layers are tested at wavelength 532 nm. A transmittance of 96.5% at single surface and a stress as low as 38 MPa are achieved. The LIDT of the anti-reflection coating is limited by the additional defects introduced at the film interfaces. This design takes advantage of the power resistance of IBS/ALD coatings and their contrary stresses, providing a concept towards the application in high power laser systems.