In-situ high temperature laser-induced damage of sol-gel Ta2O5 films with different dual additives

Abstract

Using TaCl5 as the precursor, two types of Ta2O5 sols were synthesized with employment of different dual additives, namely, diethanolamine (DEA) with acetylacetone and DEA with polyethylene glycol (PEG). The prepared sol-gel Ta2O5 films were featured by the low surface roughness, high transmittance, low absorption and high laser-induced damage threshold (LIDT). The highest LIDT of 29.1 J/cm2 was obtained in the film prepared with the DEA and PEG additives. This should be attributed to the chelation effect of DEA and the steric hindrance imposed by PEG, which synergistically resulted in a more regular three-dimensional network structure and consequently lower film internal defects. In the case of temperature increase to 150 °C, the LIDT levels of both the films decreased. The damage morphologies indicated the defect-induced mechanism for the films irradiated either at the room temperature, or at the high temperature of 150 °C. Moreover, an evolution model was proposed to reveal the effect of dual additives on the structure of Ta2O5 films. This study was conducive to a better understanding of the fundamental laser damage mechanism and exploring the potential application of sol-gel films in high temperature environment.