分析了泵浦光纤不同锥区长度对(1+1)×1耦合器效率的影响,相同锥区长度不同泵浦臂数量对(1+1)×1耦合器与(2+1)×1耦合器效率的影响,结果表明泵浦光纤锥型区域越长,通过泵浦光纤进入信号光纤的泵浦光越多,泵浦耦合器的耦合效率越高和相同锥区长度下,泵浦臂数量越多,泵浦耦合器耦合效率越低.根据分析结果制作了(1+1)×1耦合器与(2+1)×1耦合器,通过两个(N+1)×1耦合器级联方式形成级联泵浦耦合器.测试了由两个(1+1)×1耦合器组成的级联泵浦耦合器,在总注入泵浦功率602 W的情况下输出泵浦功率564 W,级联泵浦耦合效率高达93.6%.由两个(2+1)×1耦合器组成的级联泵浦耦合器,在总注入泵浦功率1 210 W的情况下输出泵浦功率1 120 W,级联泵浦耦合效率高达92.5%,实现了千瓦级泵浦功率输出,且两种级联泵浦耦合器信号光损耗均小于0.4%.利用此方法将耦合器形成级联结构可有效提高光纤激光器系统泵浦输出能力,实现千瓦级高功率输出.

The impact of(1+1)×1 coupler pump arm numbers on the pump coupling efficiency was numerically studied.It is shown that pump coupling efficiency decreases with more pump arms built on the coupler,yet in a slightly decreasing manner.The coupling efficiencies of(1+1)×1 and(2+1)×1 couplers were studied and compared under the same tapered length and the same input mode field,it implies that large number of pump arms could have adverse impact on the total coupling efficiency.According to the simulation results,two side-pumped(1+1)×1 couplers were made and the two signal fibers were spliced to form a cascaded structure.A total output power of this cascaded-structured pump coupler was about 564 W,corresponding to a coupling efficiency as high as 93.6%.And,two side-pumped(2+1)×1 couplers were made respectively and the two signal fibers were spliced to form a cascaded structure.A total output power of this cascaded-structured pump coupler was about 1 120 W,corresponding to a coupling efficiency as high as 92.5%.The loss of (N+1)×1 cascaded structure coupler signal light were less than 0.4%.Achievied the kW class output power of pump light.