SELF-SIMILAR EVOLUTION OF SELF-WRITTEN WAVE-GUIDES

Numerical simulations show that channel waveguides can be self-written in photosensitive materials. As the waveguide evolves, its shape rema ins approximately constant, even though its depth and width change. We find an exact solution that describes this evolution, which we show t o be self-similar. A wide variety of single-peaked beams form waveguid es that converge to this solution. (C) 1998 Optical Society of America .