Intense femtosecond laser pulse interaction with ultra-low expansion glass: nonlinear responses and optical limiting effect

Abstract

In this study, the nonlinear responses and optical limiting behaviour of titanium doped silicate glass (7.5TiO2–92.5SiO2), known as ultra-low expansion (ULE) glass, are investigated. The measurements were performed by use of the Z-scan technique and monitoring of the transmitted energy of 200 fs Ti:sapphire laser pulses at a central wavelength of 800 nm. The optical power limiting threshold was measured to be about 37 µJ (peak intensity of 0.55 × 1012 W cm−2) in this sample. The decrease of transmitted intensity was about 60% compared to the theoretical linear transmission for incident pulse energies of 320 µJ (peak intensity of 21 × 1012 W cm−2). For the prediction of the experimental nonlinear behaviour results, we used the three-photon absorption and three-photon-generated free-carrier absorption model within the sample.