基于腔内偏振分束器偏振控制的线偏振掺镱双包层光纤激光器

研究了一种单双波长可切换的线偏振掺镱双包层光纤激光器结构,腔内插入可以绕光轴方向旋转的立方体偏振分束器(PBS)进行偏振控制,实现单双波长的转换。激光谐振腔由高反射率的双色镜和较低反射率(10.2%)的保偏光纤布拉格光栅(PM-FBG)构成;由于保偏光纤光栅的偏振选择反馈作用增强了偏振烧孔效应,通过调节谐振腔内偏振分束器的旋转角度实现了激光的单双波长之间的切换。利用琼斯矩阵理论分析了偏振态与旋转角度的关系,其结果与实验结果吻合。实验中输出激光的双波长为1070.08nm和1070.39nm、功率为1W、激光信噪比为48dB、斜率效率为34%、3dB带宽为0.02nm。利用格兰汤姆孙棱镜对该激光的偏振特性进行了研究:单波长运转时为线偏振激光,偏振度达13.37dB;双波长运转时为正交偏振激光。     

D-shaped fiber optic SPR biosensors based on a metal-graphene structure

We design a D-shaped fiber optic biosensor based on the surface plasmon resonance （SPR） of a metal- graphene layer and simulate this SPR using the finite element method. Using a metal-graphene layer as the sensing material, surface plasma resonance is simulated as the refractive index of the external environment ranges from 1.33 to 1.36. Simulation results show that a metal-graphene layer attached to the D-shaped optical fiber core can couple with light under a specific polarization state and excite strong plasma os- cillations on the layer surface. Calculated transmission coefficients show that the resonance wavelength obviously moves toward longer wavelengths as the refractive index of the test medium increases, and a sen- sitivity of 5400 nm/RIU is obtained. Because of its large surface volume ratio and good biocompatibility, graphene map be utilized in many applications in the field of biosensing.