waves constitute the surface plasmon polaritons (SPPs). The enhancement of electromagnetic fields near the surface caused by the excitation of SPPs has generated practical applications in sensor technology [@Homola; @Kneipp; @Kurihara]. These applications include thin film probing [@Pockrand], biosensing [@Liedberg] and biological imaging [@Okamoto1]. In the Otto or Kretschmann configuration, the SPPs are excited by attenuated total internal reflection by enhancing the momentum of the incident light [@Yeatman; @Torma].

The excitation of SPPs in the Otto or Kretschmann configuration affects the GH shift profoundly. Early results on the influence of SPPs on the shift of light beams can be found in [@Mazur] and [@Kou]. It has been shown that the interaction of leaky waves with SPPs enhances the GH shift. Results on the excitation of surface waves in the Otto configuration have been reported by Chen [*et al.*]{} [@Chen]. Chuang has conducted an analysis of the behavior of the reflection coefficient for both Otto and Kretschmann configurations [@Chuang]. The zeros and poles of the reflection coefficient move around the complex plane with the change of parameters, such as the beam width, the wavelength, the thickness and the dielectric constants. Zeller [*et al.*]{} have shown that the coupling of an incident 