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Abstract: HfO2 films, using metal hafnium as starting material, are deposited by plasma-ion assisted electron evaporation with different Advanced Plasma Source (APS) bias voltages. The refractive index and extinction coefficient are calculated, the chemical state and composition, as well as the stress and aging behavior is investigated. Laser induced damage threshold (LIDT) and damage mechanism are also evaluated and discussed. Optical, structural, mechanical and laser induced damage properties of HfO2 films are found to be sensitive to APS bias voltage. The film stress can be tuned by varying the APS bias voltage. Damage morphologies indicate the LIDT of the HfO2 films at 1064nm and 532nm are dominated by the nodular-defect density in coatings, while the 355nm LIDT is dominated by the film absorption. HfO2 films with higher 1064nm LIDT than samples evaporated from hafnia are achieved with bias voltage of 100V. [Copyright &y& Elsevier]

• Deeper understanding of moisture-induced instability of electron-beam coatings was achieved by prolonging the originally rapid water adsorption process with a dense capping layer. • Water transport in electron-beam coatings included four steps: filling, stabilization, swelling and refilling. • Water molecule content and structure evolution led to the increasing compressive stress evolution at the first stage and subsequent transition from compressive to tensile stress evolution. • A model based on the finite element method was proposed to calculate the water vapor transmission rate of electron-beam coatings. The moisture-induced instability of electron-beam (e-beam) coating can even result in the performance instability of a large laser system. A dense plasma-ion-assisted-deposition SiO 2 capping layer was employed to isolate the top surface of the coating from ambient humidity and extend the originally rapid water adsorption process, allowing a deeper understanding of the instability of e-beam coatings caused by moisture. Spectral measurements suggested that four water adsorption steps, including filling, stabilization, swelling and refilling, led to the overall redshift and short-term fluctuations in spectra. The stress and Fourier transform infrared analysis revealed that water adsorption and ice-like/ice structure water was responsible for the increasing compressive stress evolution at the first stage and subsequent transition from compressive to tensile stress evolution, respectively. A model based on the finite element method was proposed to calculate the water vapor transmission rate of e-beam coatings. Our study on the underlying mechanism of moisture-induced instability of e-beam coating is helpful to ensure the reliability and stability of large laser systems. [ABSTRACT FROM AUTHOR]