Laser written waveguides in glasses and crystals

Summary form only given. Waveguides for integrated optical applications are usually made by indiffusion of ions into crystal or glass materials. However, the generation of three-dimensional structures is hard to achieve. This problem can be overcome by laser generated waveguides. Ultrashort laser pulses focused inside optical transparent bulk materials create local structural changes and in consequence of this a refractive index gradient. The result of moving the sample through the laser beam is a refractive index profile like in a buried waveguide. This direct writing method offers the potential for three-dimensional structures and allows integrated optics in different materials. The laser pulses that we used to induce refractive index changes were obtained from a regeneratively amplified Ti/sup 3+/:Al/sub 2/O/sub 3/ laser. The duration of the 780 nm pulse was 120 fs and the repetition rate of the laser was 1 kHz. The laser beam with a pulse energy of a few microjoules was focused into the material. The sample was fixed on a computer-controlled XYZ stage waveguide. Generation of waveguides in fused and crystal silica is presented. Properties of the waveguides are discussed.