Optical properties of infrared femtosecond laser-modified fused silica and application to waveguide fabrication

We investigate the changes in the optical properties of fused silica exposed to intense infrared femtosecond pulses. The laser-induced absorption spectrum reveals the creation of color centers inside the glass matrix, comparable with those observed in ultraviolet-exposed fused silica. The laser-induced absorption is associated with a laser-induced refractive-index change, which can be used for waveguide fabrication. The change in third-order susceptibility in such waveguides is measured by third-harmonic-generation microscopy as a function of the irradiation parameters.