Goos–Hänchen effect around and off the critical angle

A general expression for the Goos–Hänchen lateral shift of a Gaussian wave beam, applicable for incident angle θ equal to, near, or larger than the critical angle θc, is obtained. It yields finite and smooth results around θc and coincides with Artmann’s classical result otherwise. Another expression for the lateral shift of a different beam-field distribution is also obtained and shown to be quite similar to that of the Gaussian beam. Comparisons with an existing theoretical expression and with available experimental data (for θ ≃ θc) are made. Discussion of a different expression for θ away from θc obtained through an energy method is also presented.