| 摘要 |
A double cladding fiber includes an inner core doped with active species, an inner cladding disposed adjacent said inner core for receiving pumping energy, minimizing local modes in said inner cladding, and transferring said pumping energy to the core. An outer cladding is disposed adjacent the inner cladding. The cross section of said inner cladding has a polygon-like shape with its boundary being a plurality of well-defined arcs, each of the arcs having substantially different arc center for delivering energy with maximum efficiency to the inner core meeting the limitation of: <paragraph lvl="0"><in-line-formula>(1-L/r1)(1-L/r2)<0, </in-line-formula><paragraph lvl="0"><in-line-formula>or </in-line-formula><paragraph lvl="0"><in-line-formula>(1-L/r1)(1-L/r2)>1; </in-line-formula>where r1 and r2 is the arc radius of the inner cladding surfaces that are opposite to each other (mirror pair), with the radius of a concave mirror being positive and that of a convex mirror being negative, L is the distance between two mirrors.
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