Abstract: Guided adiabatic bend transitions for multimode fibers are presented to preserve the power of guided light in the fundamental mode while guiding from one level of curvature to another for improved operation of mode filters and fiber amplifiers. A method is provided to find the guidance path. Implementations of these transducers include modal power back converters, and guidance paths into and out of higher order mode filtering devices which work on bending. A spiral structure is shown to incorporate adiabatic bends for a forward-pumped fiber amplifier.

Abstract: The present invention provides an amplified spontaneous emission fiber optic source having high optical power (>20 mW) and a spectral broadband emission (>70 nm) centered near a wavelength of 1060 nm. In an embodiment of the invention, the fiber source comprises a combination of Yb-doped and Nd-doped silica fibers in a dual-pumping configuration. The Yb-doped optical fiber has a peak absorption coefficient of 350 dB/nm at 977 nm band, and the Nd-doped fiber used has a dopant concentration of 500 ppm-wt in a glass host of aluminum-germano-phospho-silicate. A combination of these two doped-fibers along with optical spectral filtering provides a broadband spectrum giving coherence length <7 ?m (in air), which is well suited for optical coherence imaging.

Abstract: Guided adiabatic bend transitions for multimode fibers are presented to preserve the power of guided light in the fundamental mode while guiding from one level of curvature to another for improved operation of mode filters and fiber amplifiers. A method is provided to find the guidance path. Implementations of these transducers include modal power back converters, and guidance paths into and out of higher order mode filtering devices which work on bending. A spiral structure is shown to incorporate adiabatic bends for a forward-pumped fiber amplifier.