Article utilizing optical waveguides with anomalous dispersion at

Abstract

Properly designed optical waveguides exhibit anomalous (positive) dispersion over a continuum of visible and near infrared wavelengths and, in one embodiment, the fiber has zero-dispersion at a visible wavelength (e.g., about 760 nm). Preferably, the zero-dispersion point occurs at a vis-nir wavelength where the normal (negative) material dispersion is relatively high and the effective refractive index difference between the core and the cladding is sufficiently large that the anomalous (positive) waveguide dispersion compensates the normal material dispersion. Illustratively, the optical waveguide is a microstructured fiber comprising a solid silica core surrounded by an inner cladding that includes a plurality of capillary air holes that allow for index-guiding within the core. The pattern formed by the cross-sections of the air holes, typically circles, may take on a variety geometric configurations, such as a closely packed hexagon or triangle. Alternatively, the cross-section of the air holes may form two mating, essentially semicircular regions on either side of a core that is supported by a pair of radial webs. As a result of the novel dispersion characteristics of the microstructured fibers combined with small effective area cores, we have demonstrated several applications of the invention that, in the prior art of standard single-mode fibers, have been possible only at wavelengths greater than about 1300 nm, including pulse compression, bright soliton propagation, fundamental mode-to-fundamental mode second harmonic generation, and broadband continuum generation in the visible.