Fiber-optic surface waveguide resonance in gaseous medium: Tunable generation with all fiber modes

The integration of metal clad with dielectric waveguide offers numerous advantages for generating optical surface waves. Here we perform a comprehensive study on the principle and tunable characteristics of fiber-optic surface waveguide resonances (SWRs) excited with a metal-clad film waveguide deposited on optical fiber in gaseous medium. A versatile approach is proposed for the analysis of fiber-optic SWRs and it is also available for analyzing other kinds of optical surface waves. The essential mechanism for generating surface waveguide modes is obtained. The results show that the film waveguide supports both P- and S-polarized discrete surface waveguide modes including guided modes, cladding modes and leaky modes. It is found that the introduction of a metal clad strengthens the guidance of these modes and enhances the mode coupling with fiber modes. This makes it possible to generate strongly polarization-dependent fiber-optic SWRs with all fiber modes by simply tailoring the thickness of film waveguide.