Billiard-ball soliton interaction gates

We demonstrate a cascadable, Boolean complete, conservative-logic interaction gate that is based on elastic collisions between temporal solitons in optical fibers. The two identical-frequency and polarization inputs are initially separated by 4.5 pulse widths, and they interact in a 7.5 walk-off length of polarization-maintaining fiber. The group velocity of one of the inputs is altered by passing the pulse through a beam splitter with a wavelength-dependent reflection coefficient. Although details within the interaction region depend on the phase between the two inputs, after the pulses separate the result is phase independent. We find that each of two 17-pJ solitons is displaced after interaction by 3.5 pulse widths so as to increase the pulses' separation.