Abstract:

In micro - nano optics，Goos-Hänchen( GH) shift is an important phenomenon. Stationary phase

　　method is usually utilized to obtain the GH shift，but it is difficult for students to understand the underlying physical

essence.In this paper，we study the GH shift from a novel perspective.Incident and reflected light field are calculated

based on angular spectrum theory.GH shift can then be expressed by the spot shift before and after reflection.As the

stationary phase method can only be applied to the finite-aperture plane wave and Gaussian beam， the incidence of

Gaussian beam on an epsilon -near - zero material is numerically calculated for comparing with stationary phase

method.The numerical procedure can be further applied in incidence of an arbitrary beam on an arbitrary material.It

is shown that numerical results agree well with analytical results when the incident angle is far from the critical angle，

but near the critical angle， the present numerical results can be used to describe the GH shift of Gaussian beam

more accurately.The numerical approach can be used in the calculation of GH shift of various light beams.The work

can be of help to understand the GH shift and the applicable condition of stationary phase method.

Key words: Goos-Hänchenshift, angular spectrum, ENZ material