Patent ID: 9667023
Date: 2017-05-30
CPC Classifications: H01S

Claim:
1. A single mode (“SM”) ultra-high power fiber laser system, comprising: an unconfined delivery cable centered along a longitudinal axis; an elongated fiber booster extending through the delivery cable and structured with concentric and coextending multimode (“MM”) core and at least one cladding around the MM core, the MM core being non-uniformly shaped and including a mode transition region expanding between small diameter input and large diameter output uniformly shaped MM core regions and configured so that as a SM signal light is guided in a propagating direction along the MM core, amplification of high order modes is substantially suppressed; a laser head directly receiving an output end of the booster; a plurality of unconfined pump light output fibers spaced from one another and from the delivery cable, each output fiber guiding MM pump light in the propagating direction; and a mirror mounted in the laser head ends and configured to redirect the pump light to the output end of the booster in a counter-propagating direction, wherein the booster emits the signal light in a kW to MW range in substantially the SM.