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

Linear Polarized Yb^(3+)-Doped Double-Clad Fiber Laser with an Intracavity Cubic Polarization Beam Splitter as Polarization Selection

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。

A single and dual-wavelength switchable linear polarization Yb-doped double-clad fiber laser configuration is proposed, in which the resonance cavity is composed of a fiber Bragg grating fabricated in a polarization maintaining fiber and a high reflectivity dichromatic mirror. A cubic polarization beam splitter （PBS） rotating around its own optical axis is inserted between the high reflection cavity mirror and the collimator in the laser cavity, which is used to adjust the polarization to realize single and dual-wavelength lasing emission. The polarization hole burning is enhanced by the selective polarization feedback from the polarization maintaning fiber Bragg grating （PM-FBG）. The relationship between polarization states and rotating angle of PBS is analyzed by using Jones matrix, which agrees well with the experimental results. The laser features wavelength of 1070.08 nm and 1070.39 nm, output power of 1.0 W, signal noise ratio of 48 dB, slope efficiency of 34%, as well as a very narrow linewidth of 0.02 nm. The polarization characteristics are studied by measuring the laser power transmitted through a Glan-Thomson polarizer. The polarization state of the laser is linearly polarized with a polarization degree of 13.37 dB when it is lasing at single wavelength, while it is orthogonal polarization laser for dual wavelength operating.