ABSTRACT
Planar waveguides can be fabricated in a wide range of crystal and glass materials by many methods. These include modification of the material refractive index, typically at or near the surface, through such techniques as ion-exchange [1], ion-implantation [2], ion-diffusion [3] and optical writing [4]. Alternatively, a waveguide may be formed by adhesion [5], deposition [6] or growth [7] of one material on another of different refractive index. These techniques generally lead to waveguides in the form of a planar thin film or, if some patterning technique is used, a planar array of channel waveguides (see figure B4.6.1).
