Generalized study on the pump light propagation in the distributed side-coupled cladding-pumped fiber with identical pump cores

Abstract

Abstract In this paper, a generalized numerical model describing the pump light propagating in the distributed side-coupled cladding-pumped (DSCCP) fibers with identical pump cores is present, with which the pump light propagation in the DSCCP fiber is analytically investigated. It is found that the local pump absorption should be smaller than the inner-cladding pump absorption of signal fiber. It is also revealed that the DSCCP fiber length for a given total pump absorption should be inversely proportional to the up-limitation of local pump absorption which decreases monotonously with the pump cores number. Furthermore, it is found that the peak pump power coupled into the signal fiber increases monotonously, while its ratio to the total pump power (i.e., normalized peak pump power) decrease monotonously with the increment of pump cores number. The dependences of pump light propagation on the coupling coefficients and the inner-cladding pump absorption of signal fiber are also discussed. We believe that these results can provide significant guidance on understanding and designing of DSCCP fiber and its lasers and amplifiers.