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E Ressayre

Publications and source records attributed to E Ressayre.

12 recordsLinked to original sources
PubMed2006

Spirals and vortex lattices in quasi-self-imaging divide-by-three optical parametric oscillators.

A linear stability analysis is derived in self-imaging cavities for which the conditions for large Fresnel number are stated. In cases of both Fabry-Pérot and ring cavities a Hopf bifurcation is predicted at finite transverse wave number. The self-imaging Fabry-Pérot resonator operates as a longitudinal multimode cavity that invalidates the mean-field model. Above the bifurcation threshold, either vortex lattices, spirals, or targets occur, depending on the Fresnel number, the input intensity, and the mistunings. The time and spatial characteristics have different scales in the case of a self-imaging ring cavity, but the same sort of patterns are reported.

Journal Article↗
PubMed2003

Patterns in a quasiconfocal optical parametric oscillator.

The formation of transverse patterns in a triply resonant optical parametric oscillator is studied both numerically and analytically for a spherical cavity close to confocality. While the pump profile is Gaussian, the signal and idler intensities may be made of many rings, either stationary or time dependent. The mode selection and the time dependence are understood with the help of the linear stability analysis. It might explain observations reported for a quasiconfocal cavity with a KTP crystal.

Journal Article↗
PubMed2002

Example of a chaotic crystal: the labyrinth.

Labyrinthine structures often appear as the final steady state of pattern forming systems. Being disordered, they exhibit the same kind of short range positional order as the Newell-Pomeau turbulent crystal. Labyrinths can be seen as a limit case of the texture of disordered rolls with a coherence length of the same order as the wavelength. In the various two-dimensional model equations we looked at, labyrinths and parallel rolls are steady states for the same parameters, their occurrence depending on the initial conditions. Comparing the stability of these two structures, we find that in variational models their energy is very close, rolls always being more stable than labyrinths. For the nonvariational model we propose a numerical experiment which displays a well defined bifurcation from parallel rolls to labyrinths as the more stable state.

Journal Article↗