Negative Goos--Hanchen Effect in Thin-Film Fabry--Perot Filter

We investigate the Goos--Hanchen effect of a Gaussian light beam reflected by the thin-film Fabry--Perot filter. It is shown that the Goos--Hanchen shift can be either negative or positive. The Gaussian-beam analysis and stationary phase method are introduced to calculate the lateral shift between the incident beam and the reflected beam at different wavelengths and to analyse the Goos-Hanchen effect in the thin-film Fabry-Perot filter. The effect of the incident beam diameter is also discussed.