Single-photon level ultrafast all-optical switching

Abstract

We demonstrate an approach to all-optical switching, where a weak beam controls a strong beam, based on three-wave mixing optical parametric amplification in a nonlinear crystal. Ultrafast switching within 400fs has been achieved with a 130fs single-photon level switch beam containing, on average, 0.75 photon/pulse, which can turn on/off a signal pulse containing 5.9×108 photons. The transverse patterns for the on and off states are well defined and the switch has a large bandwidth of up to 10nm.