A perturbation theory is developed that treats a localised mode embedded within a continuum of states. The method is applied to a model rectangular hollow-core photonic crystal fibre structure, where the basic modes are derived from an ideal, scalar model and the perturbation terms include vector effects and structural difference between the ideal and realistic structures. An expression for the...

A long-period grating (LPG) based compact optical fiber sensor working in reflection mode is demonstrated. A technique to make a mirror on the cladding region of a fiber end-face to reflect only the cladding modes was realized by growing a polymeric microtip on the core region of the fiber end-face, by photopolymerization, followed by coating the fiber end-face with an aluminum film. Using the ...

Using the beam propagation method, an analytical expression of the reflection spectra of a Kretschmann configuration is derived in order to excite hybridized surface plasmonic polaritons (HSPPs). In this configuration, the cladding is a uniaxial dielectric with the optical axis parallel to the interface. The validity of the analytical expression is confirmed by a finite-difference time-domain a...

We study the applicability of the weakly guiding approximation (WGA) to the modal analysis of an M-type optical fiber in which a ring-shaped core lies between two uniform cladding layers. Besides being dependent on the refractive indices, the accuracy of the approximation is shown to be substantially affected by the transverse dimensions of the core. The accuracy is characterized by calculating...

The dependence of optical modal gain and loss on GaN:Eu growth temperature is reported. GaN:Eu thin films were grown on Si substrates with AlGaN transition and cladding layers at temperatures ranging from 600 degrees C to 850 degrees C. The modal gain and loss in the GaN:Eu layer were a strong function of the optically active Eu atomic concentration and of the interface quality between the acti...

A simple CCD-camera spectrometer was deployed at the Los Alamos Spallation Radiation Effects Facility to characterize fast-neutron irradiation effects in several silica-based optical fibers over the wavelength range ~ 450-1100 nm. The experimental arrangement allowed optical loss spectra to be developed from remotely recovered frame grabs at various times during irradiation without it being nec...

Hollow-core photonic bandgap fibres (PBGFs) confine light within an air-core due to photonic bandgap effects. Such fibres allow for a very weak overlap between the guided mode and the fibre structure, which paves the way for novel and technologically enabling properties, such as low nonlinearity, high damage thresholds and transmission beyond silica’s own transparency window [1]. Mid-IR transmi...

A novel optical fiber having its cladding doped with Au nano-particles was developed by modified chemical vapor deposition process. Absorption peaks of the optical fiber preform and the fiber appearing at 585 nm and 428 nm, respectively were due to surface plasmon resonance (SPR) of the incorporated Au nano-particles in the cladding. The measured peak wavelength of the SPR was found to increase...

We propose a kind of photonic crystal fiber (PCF) designed with an annular core and fabricated using a single material. Characteristics of such fibers, including the mode field distributions of both the core and cladding modes, the effective mode area of the fundamental core mode, and the dispersion profile, are investigated using the finite element method. The coupling between the fundamental ...