A multimode ("MM") high power combiner, comprising: a plurality of passive low mode ("LM") fibers guiding respective outputs, the LM fibers being bundled together to define a tapered downstream end of a bundle, the downstream end having a core guiding combined MM signal light in a propagating direction, and at least one cladding; a MM combiner output fiber butted to the tapered downstream end so as to define a splice therebetween, the output fiber having a cladding surrounding a core which guides the MM signal light, the MM signal light being incident on a workpiece which partially reflects the incident MM signal light so that the reflected MM signal light is coupled into the core and cladding of the output fiber in a counter-propagating direction; and a clad mode absorber ("CMA") surrounding the downstream end of the bundle and extending over a part of the combiner output fiber, the CMA being configured with: 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 the MM signal light bled into the cladding upstream from the output fiber, an intermediary zone extending over the splice and regions of respective tapered downstream end and output fiber bordering the splice and configured to prevent decoupling of the MM signal light, and an upstream zone extending along the downstream end of the bundle, the upstream zone being configured to strip the reflected light coupled into the core of the combiner output fiber and bled through the splice into the cladding of the tapered downstream end fiber bundle. a plurality of passive low mode ("LM") fibers guiding respective outputs, the LM fibers being bundled together to define a tapered downstream end of a bundle, the downstream end having a core guiding combined MM signal light in a propagating direction, and at least one cladding; a MM combiner output fiber butted to the tapered downstream end so as to define a splice therebetween, the output fiber having a cladding surrounding a core which guides the MM signal light, the MM signal light being incident on a workpiece which partially reflects the incident MM signal light so that the reflected MM signal light is coupled into the core and cladding of the output fiber in a counter-propagating direction; and a clad mode absorber ("CMA") surrounding the downstream end of the bundle and extending over a part of the combiner output fiber, the CMA being configured with: 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 the MM signal light bled into the cladding upstream from the output fiber, an intermediary zone extending over the splice and regions of respective tapered downstream end and output fiber bordering the splice and configured to prevent decoupling of the MM signal light, and an upstream zone extending along the downstream end of the bundle, the upstream zone being configured to strip the reflected light coupled into the core of the combiner output fiber and bled through the splice into the cladding of the tapered downstream end fiber bundle. 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 the MM signal light bled into the cladding upstream from the output fiber, an intermediary zone extending over the splice and regions of respective tapered downstream end and output fiber bordering the splice and configured to prevent decoupling of the MM signal light, and an upstream zone extending along the downstream end of the bundle, the upstream zone being configured to strip the reflected light coupled into the core of the combiner output fiber and bled through the splice into the cladding of the tapered downstream end fiber bundle.