Device for Incoherently Combining Lasers

Incoherently combining light from different lasers while maintaining high brightness is challenging using conventional fiber bundling techniques, where fibers from different lasers are bundled adjacently in a tight-packed arrangement. The brightness can be increased by tapering the tips of the bundled fibers to match a single, multi-mode output fiber, e.g., one whose core that is just wide enough to fit the input cores. This increases the brightness of the beam combining. In addition, reducing the outer diameters of the signal fiber claddings allows the signal fibers to be bundled closer together, making it possible to couple more signal fiber cores to the core of a multi-mode output fiber. Similarly, reducing the outer diameter of the pump fiber cladding and/or etching away corresponding portions of the signal fiber cladding in a pump/signal combiner makes it possible to couple more pump light into the signal fiber cladding, again increasing brightness.