SINGLE-MODE, OPTICAL-FIBER SENSORS AND TUNABLE WAVELENGTH FILTERS BASED ON THE RESONANT EXCITATION OF METAL-CLAD MODES

The resonant excitation of metal-clad modes, including fundamental and higher-order modes, in a multilayer structure deposited on the polish ed cladding of a single-mode optical fiber is theoretically analyzed a nd experimentally demonstrated. The excitation of metal-clad modes is shown as a resonant power transfer from the fiber to the metal-clad mo de that takes place for an external refractive-index value such that t he effective index of the metal-clad mode reaches the cladding level. The observed attenuation on the TM polarization provides a suitable tr ansducing mechanism for refractive-index sensor devices as well as the principle for developing tunable wavelength-polarized filters with a wide range of optical performance characteristics.