An apparatus includes a plurality of input fibers including one or more signal fibers and one or more beam dump fibers, a signal combiner having an input end coupled to the plurality of input fibers so as to couple portions of one or more signal beams respectively propagating in one or more of the signal fibers to form a combiner beam, an output fiber coupled to an output end of the signal combiner so as to receive the combiner beam, and a beam dump coupled to at least one of the one or more beam dump fibers so as to receive a light beam propagating from the output fiber that is associated with the combiner beam.