Review of all-fiber signal combiner for high power fiber lasers(Invited)

All-fiber signal combiner is one of the key components to break through the power scaling limitation of a single fiber laser by combing several high power fibers into a single fiber to realize the higher output power. The basic structures and the research progress of the all-fiber combiner at home and abroad were sumarized. The technical program and features were discussed in detail, existing problem and future research direction were put forward.