Ageing of optical components under laser irradiation at 532nm

Abstract

The pulsed Laser Induced Damage Threshold (LIDT) of optical components usually reaches several hundreds of MW/cm². When exposed to laser power several order of magnitude below their LIDT, the optical component lifetime is, by default, considered infinite.Under specific conditions, the accumulation of laser pulses may lead to a contamination of the surface and a degradation of its optical properties and LIDT. In the first order, these phenomena depend on the experimental conditions such as the irradiation time, the laser power, and the environment.In order to better understand the physics emphasizing this degradation, we developed an experimental cell with an in-situ spectroscopic ellipsometry diagnostic. The dry-pumped cell sheltering the sample is associated with a mass spectrometer that enables us to follow the environmental conditions in which we experiment the ageing. Anti-reflection coatings on fused silica were tested under 10 kHz-532 nm laser ageing. We present first results of degradation obtained in these conditions.