LOCALIZATION PROBLEM IN OPTICS - NONLINEAR QUASI-PERIODIC MEDIA

We have presented a detailed numerical study of the localization problem in a nonlinear quasiperiodic structure for normal incidence of plane-polarized light. The main conclusions are as follows. Strong surface localization, which is observed for forbidden states (transmission coefficient T0) in the linear theory, is strongly affected even by weak nonlinearity, resulting in inhibition of localization, while the extended states corresponding to allowed regions (T1) in the linear theory retain their distribution pattern. Depending on nonlinearity, forbidden regions may exhibit critical-state behavior. The evidence of bulk localization is apparent from the nature of solitonlike field distributions for allowed regions. The bulk localization, which is a result of a delicate interplay between dispersion and nonlinearity, persists for a very large number of layers in contrast to linear theory. The bulk localized states have been shown to be self-similar. © 1990 The American Physical Society.