Net lateral shift of reflected beam in prism-waveguide coupling system due to guided wave resonance

When guided wave resonance occurs on the prism-waveguide coupling system (PWCS), the reflected beam undergoes angular shift which contributes to lateral shift of the reflected beam, in addition to the Goos-Hänchen (GH) lateral shift. We investigate the net lateral shift of the reflected beam at the Rayleigh range where the beam waist does not broaden obviously. It is shown that the incident angle associated with the maximum net lateral shift deviates from the resonant angle and the maximum net lateral shift is larger than GH shift. And at the same time, the net lateral shift is more sensitive than GH shift to the changes of PWCS parameters. Numerical simulation shows that the theory agrees well with numerical results when the beam width is large enough.