Ultrafast-infrared-laser writing SiON channel waveguides

Direct-laser writing waveguides on silicon-based materials is a one-step fabrication approach that has attracted considerable interest in photonics research. This technique involves a laser beam that is focused inside a transparent material which produces a permanent change in the refractive index of medium. In this paper we present results of channel waveguides fabricated on silicon oxynitride material by using infrared femtosecond laser pulses. This approach is based on Si/SiO ₂/SiON/SiO ₂ planar waveguides previously fabricated by means of ECR-PECVD technology. Silicon oxinitride (SiON) films on silicon substrates are very promising materials for passive or active channel waveguides for low-cost integrated optics since they are compatible with silica fibers used in telecom. We explore here how focusing femtosecond radiation on the Si ₃N ₄ planar waveguide it is possible to modify in several ways the guiding structure and particularly to define channel waveguides on this material.