Substituting scheme for nonlinear couplers

摘要

We propose a substituting scheme for nonlinear optical couplers operating by means of degenerate parametric down-conversion with strong coherent pumping. The scheme, which provides the same unitary input-output transformation as the original coupler, consists of simple linear and nonlinear optical devices: beam splitter and optical parametric amplifiers. Using group theoretical approach, we find analytical formulas for parameters of these optical elements. The scheme allows us to get a better insight into the coupler behaviour, because the complex dynamics of the coupler is transformed into a sequence of simpler evolutions governed by the beam splitter and parametric amplifiers, whose properties are well known and understood.