Transverse Dynamics in Nonlinear Optics: a Study of Illuminated Planar Systems.
Abstract
We investigate a class of systems in nonlinear optics that can exhibit transverse instability when illuminated by a single beam. The nonlinearity is confined to a plane transverse to the beam, which results in a simple theoretical description of the instability. We first consider a nonlinear thin film between arbitrary isotropic media, and find that this system can be unstable to fields in the plane of the film. This instability evolves into a periodic intensity pattern that represents a true symmetry breaking of the system, since it is present for a uniform incident plane wave and requires no external feedback. Sufficient feedback is provided by the interaction between the nonlinearity and the fields at the interface of the material. Next, we consider a nonlinear waveguide irradiated by a normally incident beam. We demonstrate an instability of a similar nature for this system, but due to the simplicity of the waveguide mode structure we are able to study the instability and its evolution in much more depth. We show that instability is produced by a conjugate interaction between two counter -propagating fields in the waveguide, and is intimately related to phase conjugation. Finally, we consider the same waveguide system but with an added grating that can also mix the two counter-propagating fields. Although this system is only described by two simple coupled mode equations we find that it can exhibit a large variety of phenomena including pattern formation, self-oscillation, spatial bistability, and chaos.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 1990
- Bibcode:
- 1990PhDT.......101R
- Keywords:
-
- Physics: Optics