Ultra high power single mode fiber laser system

Abstract

An ultra high power fiber laser system includes a single-piece fiber booster configured with fiber and straight short rod fiber portions which have in common a core configured with a numerical aperture equal to or higher than 0.1 and doped with ions of one or more rare earth elements across the entire cross-section thereof. The rod fiber portion is structured with a short length not exceeding about a few tens of centimeters and has a generally frustoconical cross-section expanding from the uniformly configured fiber portion. The core extending along the fiber portion is capable of supporting either a SM or a very low number of HOMs guided along the core in a propagating direction and coupled into the small diameter end of the rod fiber's frustoconically-shaped core. The opposite, large-diameter end of the frustoconical core supports multiple modes with a fundamental mode overlapping at least about 0.652 of the cross-section area of the core along the entire length thereof. The disclosed power system further includes a pump source emitting high power multi-mode pump light which is coupled into the large- diameter end of the core in a counter propagating direction with a NA of at most equal to the NA of the core. The pump is configured to emit pump light with such a density that while amplification of the fundamental mode continues in the overlapped area of the core, a peripheral, non-overlapped area of the core is bleached. As a consequence, the disclosed system emits signal light in substantially a fundamental mode with an average power of several kWs in a CW regime or peak power of about one or more MWs in a pulsed regime of the system's operation.

Description

technical field [0001] The present disclosure relates to single-mode ("SM") ultra-high power fiber laser systems emitting a substantially fundamental mode output with peak power in the order of MW and average power in the order of kW. Specifically, the disclosed SM fiber optic system includes: a fixed housing with a pump source and a seed source; a laser head spaced apart from the housing; an unconfined delivery fiber between the housing and the laser head and a booster extending at least partially through the delivery fiber and having a downstream end directly connected to the laser head. Background technique [0002] The dramatic increase in output power from rare earth-doped fiber sources dates back decades, and the use of double-clad fibers has enabled many fiber laser systems to achieve superior performance in terms of output power, beam quality, overall efficiency, and wavelength flexibility. However, the power range of modern high-power fiber laser systems still cann...

AI Technical Summary

Problems solved by technology

Specifically, air holes slow the spread of heat, which in turn can damage the rod itself and cause environmental disaster

[0017] In summary, the design of high power fiber optic systems faces many difficult challenges due to: nonlinear effects in fibers in general (fiber rods in particular), loss of fundamental mode power to higher order modes ("HOMs"), pumping Brightness (pumpbrightness), and of course excessive heat generation

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