Patent attributes
An optical fiber combiner comprises a double-clad fiber (DCF) and one or more multimode fibers (MMFs). DCF comprises a transition portion, a first taper portion, and an output section coupling to the first taper portion, whereas each of MMFs comprises a second taper configured to be fused around DCF in the transition portion. MMFs are configured to carry a combined optical energy (COE) and to couple to DCF. COE passes through the second taper with larger divergence of higher-order modes generated and coupled into DCF, whereas the first taper portion can partially offset the larger divergence. COE coupled, when traced through the output section, emerges in air with a smaller output beam divergence of the higher-order modes, thereby preserving some of the higher-order modes in the output section and increasing a coupling efficiency of COE coupled from MMFs to DCF with improved thermal performance.