Comparative study on the continuous-wave double-cladding Yb-doped fiber amplifiers operating around 978 nm and 982 nm

Abstract

The comparative study on the continuous-wave double-cladding Yb-doped fiber (DCYF) amplifiers operating around 978 nm and 982 nm is carried out in this paper. By means of numerical and experimental studies, it is revealed that compared with 978-nm amplifiers, the amplified spontaneous emission (ASE) around 1030 nm can be better suppressed in 982-nm amplifiers because of the lower requirement of population inversion for the amplification of 982-nm signal light, and thus, the larger optimum active fiber length and slope efficiency can be obtained in 982-nm amplifiers. This should be the first experimental demonstration that the slope efficiency of 982-nm amplifiers can be larger than that of 978-nm amplifiers, to the best of our knowledge. The effect of signal wavelength on the slope efficiency of amplifiers is also numerically studied. It is found that the optimum signal wavelength varies from the 982 nm to 980 nm with the increment of pump light. It is also found that the variation of optimum fiber length with the pump power in the case of signal wavelength longer than 986 nm is different from that with the signal wavelength shorter than 984 nm. The pertinent explanation is also given.