双包层光纤中模式能量分布状态对泵浦光吸收效率的影响

Impact of Energy Distribution of Modes in Double Clad Fiber on Pumping Light Absorption Efficiency

从模式理论出发,采用二阶伽辽金有限元法,数值计算了圆型和D型内包层两种双包层光纤中前200个模式的纵向光功率分布状态;研究了其各模式能量分布状态对泵浦光吸收效率的影响,结果表明:圆型内包层中各模式的能量分布均具有圆对称特性,但其中只有LP0n模式对泵浦吸收起作用,其它高阶模式对稀土离子抽运都没有实际贡献;D型内包层中的直边边界条件能够有效打破圆对称分布状态,由圆对称变成了轴对称,其绝大多数模式都能起到对稀土离子的抽运作用,具有很高的泵浦吸收效率.

Using the 2nd Galerkin finite element method,the impact of energy distribution of modes in the inner cladding of circular-shape and D-shape double clad fibers on pumping light absorption efficiency was studied theoretically based on mode theory.The result showed that:energy distribution of modes in circular-shape inner cladding had the characteristics of circular symmetry,and only LP0 nmodes can be absorbed directly by rare-earth doped core;the beeline boundary condition of D-shape inner cladding can break the circular symmetry which made energy distribution of modes had the characteristics of axial symmetry,and almost every mode in the D-shape double cladding fiber can contribute to the absorption efficiency.