All-Optical Switching with Transverse Optical Patterns

TL;DR

This paper presents an ultra-low-light all-optical switch using transverse optical patterns in rubidium vapor, capable of cascadable operation and transistor-like signal restoration, with potential for practical optical logic applications.

Contribution

It introduces a novel all-optical switching mechanism operating at extremely low light levels with cascadability and signal restoration features, advancing optical network technology.

Findings

Operates at 10^{-2} photons per cross section

Induces pattern change with less than 1 mW pump power

Exhibits cascadability and transistor-like behavior

Abstract

We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features necessary for use in optical switching networks. An input switching beam, wavelength $\lambda$, with an energy density of $10^{-2}$ photons per optical cross section [$\sigma=\lambda^2/(2\pi)$] changes the orientation of a two-spot pattern generated via parametric instability in warm rubidium vapor. The instability is induced with less than 1 mW of total pump power and generates several $\mu$Ws of output light. The switch is cascadable: the device output is capable of driving multiple inputs, and exhibits transistor-like signal-level restoration with both saturated and intermediate response regimes. Additionally, the system requires an input power proportional to the inverse of the response time, which suggests thermal dissipation does not necessarily limit the practicality of optical logic devices.