Laser Induced Damage Threshold of Ta2O5 and Ta2O5/SiO2 Films at 532 and 1064 nm

Laser induced damage threshold (LIDT) of conventional electron beam deposited Ta2O5 and SiO2 thin films on BK-7 substrate are studied to see the effect of multilayer boundary and related effect for their combination as high and low index material films when number of layers increases as well as improvement on upper two non-quarter wave thickness layers. Reflection spectra of these samples show a relatively small decrease in reflection in non-quarter wave layer design and Grazing Incidence X-ray Diffraction (GIXRD) patterns show that deposited films are amorphous, having high (4.2 eV) band gap, sufficient high refractive index and very low extinction coefficient or low absorption which are factors favourable for high laser induced damage threshold. LIDT measured for single layer at 1064 nm is higher than that of multilayers and vice-versa at 532 nm wavelength. However, improvement of LIDT with non- quarter wave outer layers is more at 532 nm than 1064 nm.