Tapered Fiber Bundle 7$\,\times\,$1 End-Pumping Coupler Capable of High Power CW Operation

A high efficiency tapered fiber bundle (TFB) 7 × 1 end-pumping coupler with a handle pumping power of 3.01 kW and a coupling efficiency of 99.4% was reported. The coupling efficiency of the TFB 7 × 1 end-pumping coupler is calculated by the 3-D beam propagation method. According to the theoretical results, the excellent TFB 7 × 1 end-pumping coupler is manufactured successfully in experiment.