Densification of silica glass induced by 0.8 and 1.5 Ám intense femtosecond
A. Saliminia, N. T. Nguyen, S. L. Chin, and R. Vallée
Center for Optics, Photonics, and Laser (COPL), Laval University, Québec G1K 7P4, Canada
(Received 20 September 2005; accepted 14 March 2006; published online 12 May 2006)
We investigate the physical mechanisms responsible for waveguide formation in silica glass induced by 1 kHz intense femtosecond laser pulses from a Ti-sapphire laser at 0.8 Ám as well as from a femtosecond optical parametric amplifier at 1.5 Ám. It is demonstrated that the densification taking place at the irradiated region is the principal cause for refractive index change in the waveguides written with both 0.8 and 1.5 Ám pulses. The birefringence induced by the stress arising from such densification and its behavior against thermal annealing are also studied.