Switching with transverse optical patterns

Two-spot patterns

When the pump beam power is near threshold, the symmetry of the generated light is weakly broken resulting in a transverse pattern containing two spots. This corresponds to two distinct output beams.© Andrew Dawes, 2005

Our switch is based on the combination of strong nonlinear interactions and transverse optical patterns. Strong nonlinear interactions allow weak beams to interact with each other thus, in principle, enabling few-photon switching. Transverse optical pattern refers to the spatial distribution of output light beams when they are projected onto a screen perpendicular to the propagation direction. These patterns (and thus the output beams) are very sensitive to weak perturbation from additional light (i.e. the switching beam). This allows a weak switching beam to control a much stronger output beam.

As discussed in the Patterns section, our experimental system consists of laser beams that counterpropagate through a rubidium vapor and induce an instability that in turn generates new beams of light. The patterns formed by projecting these beams onto a transverse plane can be controlled by perturbing the system.

... and with a switching beam

An animation indicating the effect of a weak switching beam directed along the cone. When the switching beam is on, the spots rotate by 60° to a new orientation. The panes in the lower right are examples of experimentally observed patterns with and without the switch beam.© Andrew Dawes, 2005