Role of evanescent waves in the positive and negative Goos-Hänchen shifts with left-handed material slabs.

A generalized analytical formulation for analyzing the Goos-Hänchen (GH) lateral shift direction is provided, from which we show that the phenomenon of both positive and negative GH shifts at different incident angles can be observed with left-handed material (LHM) slabs. The formulation also reveals that this unique phenomenon is related to the relative amplitudes of the growing and decaying evanescent waves inside the LHM slabs. The energy flux patterns with LHM slabs are further studied to show the influence of the evanescent waves on the GH shift direction change. [ABSTRACT FROM AUTHOR]