Nd^(3+)/Yb^(3+)共掺磷酸盐玻璃光纤的发光与激光特性研究  

Stimulated emission and laser behaviors of NdNd^(3+)/Yb^(3+)Co-doped phosphate glass fiber

作　　者：林治全 于春雷[1] 何冬兵[1] 冯素雅[1] 张磊[1] 陈丹平[1] 胡丽丽[1] 

机构地区：[1]中国科学院上海光学精密机械研究所强激光材料重点实验室，上海 201800 [2]中国科学院大学，北京 100049

出　　处：《物理学报》2017年第16期116-125,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61405215;61505232);中国科学院青年促进会;国家高技术研究发展计划(批准号:2016YFB0402201)资助的课题~~

摘　　要：以970 nm和808 nm半导体激光器作为抽运源,从光纤长度和抽运功率两个方面,探讨了Nd^(3+)/Yb^(3+)摩尔浓度比约为4:1的共掺磷酸盐玻璃光纤的发光与激光特性.在970 nm抽运下,光纤光谱以Yb^(3+)离子的发光为主,但Yb^(3+)→Nd^(3+)能量传递会对光纤光谱(激光和受激放大自发辐射)产生调制作用,调制作用随970 nm抽运功率或光纤长度的增加而显著,甚至出现显著的双波长激光现象.尽管玻璃样品中Nd^(3+)→Yb^(3+)的能量传递效率ηNd→Yb高达64%,但在808 nm抽运下,激光峰始终在1053 nm附近产生,且与808 nm抽运功率大小和光纤长度无关.为解释这一现象,推导了考虑Nd^(3+)离子受激辐射的能量传递模型.从理论模型来看,Nd^(3+)→Yb^(3+)能量传递作用随Nd^(3+)离子受激辐射信号光强度的增加而迅速减弱,这与该光纤实际测试的荧光光谱随808 nm抽运功率的变化规律相符合.因此,当采用Nd^(3+)离子来敏化Yb^(3+)离子时,需要考虑Nd^(3+)离子的受激辐射对Nd^(3+)→Yb^(3+)能量传递的抑制作用.The energy transfer phenomenon between Nd3＋and Yb3＋generates the research interest in Nd3＋/Yb3＋co-doping, because it provides a straight-forward way to combine the features of Nd3＋ and Yb3＋ to develop some potential appli-cations, such as solar cells, high energy pulse and tunable lasers. Substantial research work has been conducted to study the spectroscopic properties of Nd3＋/Yb3＋ in different glasses, crystal and ceramic host materials. However, it is still not very clear about the laser properties of the Nd3＋/Yb3＋ co-doping system, especially the high rare-earth solubility phosphate glass. This work reports the stimulated emission and laser properties of an Nd3＋/Yb3＋ co-doped phosphate glass fiber under singly 970 nm and 808 nm LD pumping. The molar doping ratio of Nd3＋ ： Yb3＋ is 4 ： 1. Using the free-space coupled method, the laser properties of the co-doped fiber under 970 nm pump are tested first in a laser cavity comprised of a butt-coupled dichroic mirror with high reflectivity （≥99.5%） and a cleaved fiber ended with～4.6%Fresnel reflectivity. It is found that with the increase of 970 nm pump power （P970） two discrete laser peaks and one peak located at 1053 nm with a larger threshold can be observed for fiber length equal to and less than 0.7 m. The 1053 nm laser is produced by Yb3＋→Nd3＋ energy transfer, and its lasing threshold decreases with increasing fiber length in this length region. Then, the amplified spontaneous emission （ASE） spectra for fiber lengths of 0.35 m, 0.9 m and 5.0 m under 970 nm pumping are tested by cutting 6？ at the output port. The test results indicate that the Yb3＋ →Nd3＋ energy transfer has a modulation effect on fiber spectrum, and the modulation becomes more obvious for a longer fiber length. A two-fold promotion mechanism is suggested to explain the modulation effect： 1） the reabsorption effect of Yb3＋ leading to relatively lifetime prolongation increases the Yb3＋ → Nd3＋ energy transfer efficiency; 2�

关 键 词：光纤激光器 磷酸盐玻璃光纤 Nd^(3+)■Yb^(3+)能量传递 

分 类 号：TN24[电子电信—物理电子学] TQ342.82[化学工程—化纤工业]