Ultrafast digital soliton logic gates

Abstract

We demonstrate all-optical fibre switches, including soliton-dragging logic gates, soliton-interaction gates and soliton-trapping AND-gates, that have the potential of operating up to speeds of 0.2 Tbps. Solitons in fibres are attractive for ultrafast timedomain switching because they avoid pulse distortion during propagation and because they exhibit particle-like properties. Soliton-dragging logic gates satisfy all requirements for a digital optical processor and having switching energies approaching 1 pJ. In addition, soliton-dragging logic gates are one example of a more general timedomain chirp switch architecture in which a dispersive delay line acts as a ‘lever-arm’ to reduce the switching energy. Soliton-interaction gates are based on elastic collisions between solitons and illustrate that solitons can be used to implement conservative, billiard-ball logic operations. Soliton-trapping AND-gates are sensitive to the timing of the input pulses and display on/off contrast ratios greater than 20∶1. The soliton-trapping AND-gate can serve as the final stage in an all-optical system and as the interface to electronics. These ultrafast gates may prove advantageous in applications where the switch bandwidth limits the performance of the system