Properties of femtosecond laser modified e-beam deposited SiO2 films and their resistance to nanosecond ultraviolet lasers

The point defects exist in the SiO2 thin films can cause high absorption, which is known to be responsible for laser induced damage of the films under high power nanosecond (ns) laser irradiation. Laser conditioning of the film is beneficial to eliminate the film defects and improve the ability of films to resist ultraviolet (UV) ns laser damage. In this article, femtosecond laser is proposed to modify the SiO2 films in the hope of improving the damage resistance of films to UV lasers. After femtosecond laser conditioning, the film properties of ALD SiO2 films were characterized in terms of surface morphology, UV laser damage induced threshold (LIDT) and optical properties. The results show that significant improvement in laser damage resistance is achieved after femtosecond laser conditioning, the LIDT of the 300 nm SiO2 thin film increased from 1.55 J/cm2 to 16.69 J/cm2, and the LIDT of the 600 nm SiO2 thin film increased from 2.01 J/cm2 to 9.46 J/cm2.