Fabrication of waveguides and microfluidic channels in fused silica by a femtosecond laser

Fabrication of optical waveguides in glasses and crystals is very common for many applications in integrated optics. They are commonly fabricated by ionic exchange or diffu- sion into a transparent substrate, by laser irradiation of spe- cial photorefractive materials, or by lithographic methods. Although these technologies are well established and successful they are not very flexible in terms of geometry that can be obtained especially when three-dimensional photonic devices are required. To overcome this limitation, femtosecond lasers could offer a valid alternative to tradi- tional technologies due to the recent development of high energy density laser sources, which would allow infrared laser to interact with glass substrate as shown in. In this article, it was pointed out, for the first time, that a tightly focussed femtosecond laser can be absorbed inside a bulk glass, giving the opportunity to develop new tech- nologies in optical devices fabrications. Since then, several research groups have reported their results in fabricating many devices, in many materials, using many different laser configurations and parameters.