We describe an experiment performed to observe a new phenomenon, spatial nonlinear mode formation, in a cylindrical nonlinear cavity. These spatial nonlinear modes are analagous to spatial solitons in traveling-wave systems. The spatial nonlinear mode is observed spectroscopically, due to the binding energy caused by photon-photon interactions. Spatial nonlinear mode formation is accompanied by substantial transverse reshaping of the field transmitted through the cavity, as well as an enhanced transmissivity. A theoretical discussion of a new, related phenomenon called the optical whistle instability is presented, wherein the cavity field can oscillate when driven by a continuous light source.
Period doubling also occurs, as does choatic oscillation.
This instability occurs as a result of a mode mismatch in the spatial nonlinear mode formation process. Fabry-Perot is presented. A classical model of the phenomenon, as well as a possible experiment to observe it in the laboratory, are discussed. A connection to superfluidity is then made, and it is conjectured that photon fluids are superfluids in certain circumstances. Some ideas for detecting the superfluid nature of light are presented.