  We investigate experimentally and theoretically effects of the inter-core
propagation mismatch on nonlinear switching in dual-core high-index-contrast
soft-glass optical fibers. Incident femtosecond pulses of various energy are
fed into a single ("straight") core, to identify transitions between different
dynamical regimes, viz., inter-core oscillations, self-trapping in the cross
core, and retaining the pulse in the straight core. The transfer between
channels, which has solitonic character, is controlled by the pulse's energy. A
model based on the system of coupled nonlinear Schr\"{o}dinger equations
reveals the effect of the mismatch parameter and pulse duration on the diagram
of the various energy dependent dynamical regimes. Optimal values of the
mismatch and pulse width, which ensure stable performance of the nonlinear
switching, are identified. The theoretical predictions are in agreement with
experimental findings.
