In this paper, Er/Yb co-doped fiber amplifiers(EYDFAs) with an Yb-band fiber Bragg grating(FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity ...In this paper, Er/Yb co-doped fiber amplifiers(EYDFAs) with an Yb-band fiber Bragg grating(FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity and center wavelength of the FBG along with the gain-fiber length on the performance of an EYDFA are numerically analyzed. The results show that the wavelength of the FBG has critical influence on the efficiency of the EYDFA,whereas the requirement to its reflectivity is relaxed. It is an effective and promising way to improve the efficiency of a high-power pumped EYDFA by introducing a suitable Yb-band FBG at the pump end. Based on the analysis of the underlying principles, suggestions for the practical design and possible further improvement strategies are also proposed.展开更多
Cucullitingis biacantha gen. & sp. nov., a new genus and species of the family Tingidae is described and established based on two fossil specimens from the mid-Cretaceous Burma amber. According to the statistical res...Cucullitingis biacantha gen. & sp. nov., a new genus and species of the family Tingidae is described and established based on two fossil specimens from the mid-Cretaceous Burma amber. According to the statistical result of fossil tingids, the evolution of hood, carinae and paranota was discussed.展开更多
基金partially supported by the Natural Science Foundation of Tianjin under grant 13JCYBJC16100the National Natural Science Foundation of China under grants 61107035 and 61378043+1 种基金the National Key Scientific Instrument and Equipment Development Project of China under grant 2013YQ03091502the National Basic Research Program of China(973 Program)under grant 2014CB340104
文摘In this paper, Er/Yb co-doped fiber amplifiers(EYDFAs) with an Yb-band fiber Bragg grating(FBG) at the pump end to improve the performance of the amplifier is systematically studied. The influence of the reflectivity and center wavelength of the FBG along with the gain-fiber length on the performance of an EYDFA are numerically analyzed. The results show that the wavelength of the FBG has critical influence on the efficiency of the EYDFA,whereas the requirement to its reflectivity is relaxed. It is an effective and promising way to improve the efficiency of a high-power pumped EYDFA by introducing a suitable Yb-band FBG at the pump end. Based on the analysis of the underlying principles, suggestions for the practical design and possible further improvement strategies are also proposed.
基金supported by Joint Fund of the Beijing Municipal Natural Science Foundation and Beijing Municipal Education Commission(KZ201810028046)grants from the National Natural Science Foundation of China(31730087,41688103 and 31672323)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University(IRT-17R75)the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-year Plan(IDHT20180518)the Youth Innovative Research Team Project of Capital Normal University
文摘Cucullitingis biacantha gen. & sp. nov., a new genus and species of the family Tingidae is described and established based on two fossil specimens from the mid-Cretaceous Burma amber. According to the statistical result of fossil tingids, the evolution of hood, carinae and paranota was discussed.