LOW-MODE HIGH POWER FIBER COMBINER

摘要

A high power fiber laser system is configured with a combiner end fiber spliced to a combiner output fiber. The system further includes a light stripper extending along the combiner end and output fibers and configured with sequentially located zones which are provided with respective refractive indices. In a forward propagating direction of light signal, the upstream zone includes polymeric material with the refractive index higher than that of the cladding of the combiner end fiber. This zone is configured to remove the backreflected core guided light bled into the cladding of the combiner through a splice between combiner end and output fibers. The intermediate zone includes polymeric material configured with a refractive index lower than that of the cladding of the combiner output fiber so it can prevent clad guided signal light from decoupling the cladding under the material. The downstream zone is configured with polymeric material having a refractive index lower than that of the cladding of the combiner output fiber. The polymeric material of the downstream zone is impregnated with a plurality of light diffusers scattering high numerical aperture rays of the clad-guided signal light.

主权项

1. A low-mode (“LM”) high power combiner, comprising:
a plurality of single mode (“SM”) passive fibers guiding respective SM outputs, the SM fibers being bundled together to define a taper narrowing to an end fiber, the end fiber having a core guiding combined LM signal light in a propagating direction, and at least one cladding; a multitimode combiner output fiber butted to the end fiber to define a splice, the output fiber having a cladding surrounding a core which guides the LM light, the LM light being incident on a workpiece partially reflecting the incident light so that a portion of the reflected light is coupled into the core of the output fiber guiding the reflected light in a counter-propagating direction; and a clad mode absorber (“CMA”) surrounding the end fiber and extending over a part of the combiner output fiber, the absorber being configured with: an upstream zone extending along the end fiber and terminating at a distance upstream from the splice, the upstream zone being configured to strip a portion of the reflected light coupled into the core of the combiner output fiber and bled through the splice into the cladding of the end fiber, an intermediary zone extending over the splice and regions of respective end and output fibers bordering the splice, the intermediary zone being configured to prevent decoupling of a portion of the LM light bled into the cladding of the output fiber, a downstream, zone extending over the output fiber and terminating at a distance from a downstream end thereof, the downstream zone being configured to scatter low numerical aperture (“NA”) rays of the LM light guided along the cladding.