High-contrast modulation of light with light by control of surface plasmon polariton wave coupling

Abstract

We have demonstrated a mechanism for modulating light with light by controlling the efficiency with which light is coupled into a plasmon polariton wave. An optical fluence of $15\mathrm{mJ}∕{\mathrm{cm}}^2$ in the control channel is sufficient to achieve nearly a ten-fold intensity modulation of the signal beam reflected from a Glass $∕{\mathrm{MgF}}_2∕\mathrm{Ga}$ structure. The mechanism depends on a nanoscale light-induced structural transformation in the gallium layer and has transient switching times of the order of a few tens of nanoseconds. It offers high modulation contrast for signals in the visible and near infrared spectral ranges.