Photosensitivity in glasses: comparing ultrafast lasers with vacuum-ultraviolet lasers

Summary form only given. Laser microfabrication technology is a promising photonics processing approach with parallels to the current use of lasers in semiconductor lithography, trimming, repair, and inspection. To this end, our groups are exploring two extreme forefronts of laser technology - ultrafast (UF) and deep-ultraviolet (UV) lasers - to drive strong interactions in transparent materials for shaping photonic structures. We recently provided head-to-head comparisons of F/sub 2/-laser and 1-ps UF-laser approaches in smooth surface microsculpting of optical glasses, and introduced a new UF-laser processing mode called burst machining that offers crack-free ablation. In this paper, we present an extension to more subtle laser-glass interactions that drive internal refractive-index changes. Photosensitivity processing rates, spatial resolution, and processing windows for both laser types are discussed together with the prospects for printing and trimming of optical waveguides and circuits.