Taper Fused Fiber Bundle $1\times 4$ Coupler for High Power Splitting

The first experimental demonstration of a 1 × 4 all-fiber power splitter capable of high-power operation is presented. The splitter, prepared by fused taper technique and fusion splicing technique, consists of one input fiber with a core diameter of 400 μm (NA
_CORE
= 0.22) and four output fibers with a core diameter of 200 μm (NA
_CORE
= 0.22). The device was tested at a laser power up to 166 W and it achieves a low excess loss of 0.56 dB and an excellent uniformity of less than 0.3 dB in port-to-port power splitting ratio. The results of theoretical simulation by the 3-D beam propagation method show that the performance of this splitter could be optimized further through modifying structure parameters.