All-optical linear reconfigurable logic with nonlinear phase erasure

Abstract

We introduce a novel all-optical logic architecture whereby the gates may be readily reconfigured to reprogram their logic to implement (N)AND/(N)OR/X(N)OR. A single gate structure may be used throughout the logic circuit to implement multiple truth tables. The reconfiguration is effected by an optical reference signal. The reference may also be adapted to an arbitrary Boolean complex alphabet at the gate logic inputs and calibrated to correct gate imperfections. The all-optical gate structure is partitioned into a linear interferometric front end and a nonlinear back end. In the linear section, two optical logic inputs, along with a reference signal, linearly interfere. The nonlinear back end realizes a phase-erasure (or phase-reset) function. The reconfiguration and recalibration capabilities, along with the functional decoupling between the linear and nonlinear sections of each gate, facilitate the potential aggregation of large gate counts into logic arrays. A fundamental lower bound for the expended energy per gate is derived as $3h\nu +kT\ln 2\text{\hspace{0.17em} Joules}$ per bit.