Introduction

The study of wave interactions in periodic structures has a rich history that dates from the early days of solid-state physics through the development of coupled-wave theory. Nonlinear optics, including the physics of optical solitons, is a newer discipline that is steadily finding applications in laser engineering, communications, medicine, and many other fields. The combined study, that of nonlinear optical interactions in periodic structures, has been a significant area of study during the 1980’s and 1990’s and is the subject of this focus issue of Optics Express. The papers included in this issue represent invited submissions from research groups known to be active in theoretical and experimental studies of the nonlinear optics of periodic structures. Many of the papers in this special issue were originally presented as invited papers at the Workshop on Novel Solitons and Nonlinear Periodic Structures held in Victoria, Canada, in April 1998.

The balance between theory and experiment shows evidence of a maturing subfield. The types of nonlinearity considered in the theoretical investigations include both the well-studied third-order nonlinearities (Pereira and Sipe; de Sterke; Litchinitser et al.) as well as quadratic (Conti et al.) and semiconductor laser nonlinearities (Maywar and Agrawal). The structural variations include uniform fiber gratings, tapered and chirped gratings (de Sterke; Litchinitser et al.; and Slusher et al.), birefringent geometries (Pereira and Sipe), and planar waveguides (Maywar and Agrawal). The experiments, in turn, show a similar range both in geometry and timescale. The ultrafast nonlinearity and long path length that are available in fibers lead naturally to the study of pulse propagation effects (Broderick et al.; Slusher et al.) whereas the stronger nonlinearities and short path lengths available in semiconductors lend themselves to quasi-cw (nanosecond to microsecond) studies of switching dynamics (Coriasso et al.; Brown et al.).

Although the papers in this focus issue broadly represent the current state of knowledge, it is worth mentioning related fields that are beyond the scope of this issue. Two such fields are multidimensional photonic bandgap structures and periodic laser structures, including distributed feedback lasers. We hope, through this focus issue, that scientists in these and other related fields will find relevance in their own studies.