Figure 3
From: Integrated multi-port circulators for unidirectional optical information transport
Optical propagation dynamics in the ND elements. (a) The large nonlinearity results from the presence of electrons in the conduction band because of absorption, leading to exciton saturation as well as free-carrier-plasma and band-filling effects. The degeneracy between the two propagation eigenvalues is nonlinearly broken. (b) Simulations of optical transport in the ND elements under nonlinear (top) and linear (bottom) conditions. The amplified signal traverses the ND section within the same waveguide element because of nonlinear detuning (top), whereas at lower power levels the lightwave crosses over (bottom) in properly designed structures. (c) Experimental measurements of the output power from ND arrangements having different lengths (linear regime). These measurements are used to fabricate and design a re-routing device with an optimum extinction ratio.
