Abstract: Coupling of core modes to surface modes in an air-core photonic-bandgap fiber (PBF) can cause large propagation losses. Computer simulations analyze the relationship between the geometry and the presence of surface modes in PBFs having a triangular hole pattern and identify ranges of core characteristic dimensions (e.g., radii) for which the fiber supports no surface modes (i.e., only core modes are present) over the entire wavelength range of the bandgap. In particular, for a hole spacing ? and a hole radius ?=0.47?, the core supports a single mode and supports no surface modes for core radii between about 0.7? and about 1.05?, which suggests that such fibers should exhibit a very low propagation loss. The existence of surface modes can be predicted simply and expediently by studying either the bulk modes alone or the geometry of the fiber without requiring a full analysis of the defect modes.

Abstract: A method determines a nonlinearity profile of a material. The method includes providing a magnitude of a Fourier transform of a measured nonlinearity profile measured from the material. The method further includes providing an estimated phase term of the Fourier transform of the measured nonlinearity profile. The method further includes multiplying the magnitude and the estimated phase term to generate an estimated Fourier transform. The method further includes calculating an inverse Fourier transform of the estimated Fourier transform. The method further includes calculating a real component of the inverse Fourier transform to generate an estimated nonlinearity profile.

Abstract: A process of poling a silica material such as an optical fiber whereby electro-optic non-linearities are induced so that the material can function as a phase modulator and switch in optical communications applications. The poling is effected at an elevated temperature on the order of 450° C. or higher, using an electric field on the order of 800 V/&mgr;m or higher for a period of time in the range of one minute to several tens of minutes.

Abstract: A process of poling a silica material such as an optical fiber whereby electro-optic non-linearities are induced so that the material can function as a phase modulator and switch in optical communications applications. The poling is effected at an elevated temperature on the order of 450° C. or higher, using an electric field on the order of 800 V/&mgr;m or higher for a period of time in the range of one minute to several tens of minutes.