Lateral shift assisted by guided modes on a metal cladding planar waveguide of micrometer scale

We investigate the lateral shifts of both the reflected and transmitted beams when a Gaussian beam is incident on a symmetrical metal cladding planar waveguide of micrometer scale. Different from the other schemes, the shifts are greatly enhanced when the guided modes are excited and cannot be attributed to the Fabry-Perot like resonance. Owing to the absorption of the metal films, the lateral shifts corresponding to the reflected and transmitted beams are not the same. The displacement of the transmitted beam can be negative, by suitable adjustment of the parameters of the structure, such as the incident angle, wavelength, and etc. Near the resonance dip of the reflection spectrum, the reflected beams undergone significant distortion and may split into two parts with positive and negative shifts, respectively.