High-power Quasi-continuous Wave Operation of Incoherently Combined Yb-doped Fiber Lasers

Abstract

High-energy, high-power, quasi-continuous wave (QCW) operation of double-clad Yb fiber lasers incorporating an incoherent signal combiner is reported. We constructed four efficient, high-power Yb fiber lasers, each of which produced rectangular pulses at 1080 nm with a pulse energy greater than 15 J, and a pulse duration of 10 ms at a repetition rate of 10 Hz, corresponding to an average power of over 150 W and a peak power of over 1.5 kW for similar to 200 W of incident pump power at 915 nm. These laser outputs were combined by a homemade incoherent fiber signal combiner with low loss, yielding a maximum peak power of similar to 6.0 kW in a beam with M-2 approximate to 12.5. The detailed laser characteristics and prospects for further power scaling in QCW operation are discussed.