Influence of Thickness, Substrate and Wavelength on Laser Damage Threshold of SiO2Thin Films

Abstract

Laser damage threshold of optics is key point from the time of invention of laser. In this study the laser induced damage threshold (LIDT) of SiO2 material which is used in making high reflective (HR) coating and antireflective (AR)coating, is explored on the basis of thickness of film, substrate on which film is formed and on two different laser wavelengths which lies in Infrared IR and visible region. Samples are deposited by conventional e-beam deposition method having λ/4 and 3λ/4 thickness, on BK-7 and on fused silica. LIDT is measured in nano-second regime with Nd: YAG laser at 532nm and 1064nm, damage morphology is studied by scanning electron micrograph (SEM) and suitable damage mechanism is found out. Optical properties of the films are investigated by spectrophotometer and ellipsometry.