物理学报2017，Vol.66Issue(19)：86-94,9.DOI:10.7498/aps.66.194202
高功率光纤中传输光模式与其波长相关性研究
Analysis of wavelength dependence of mode in highpower fiber laser
摘要
Abstract
High power fiber lasers and amplifiers are widely used in the scientific and industrial field. In order to meet the requirements for high output powers the effective area of fibers becomes larger and larger to reduce optical nonlinearities. With the increase of effective area, the number of high-order modes will increase. In the case of high output power, the spectral shift and broadening of the optical fiber will also affect the modal number and content. The number and content of fiber modes affect the pointing stablity and quality of the laser beam. The M 2-parameter is commonly used to define the quality of the laser beam, but a small M 2 number is not guaranteed for single mode operation. Therefore, the relationship between wavelength and transmission mode in fiber transmission is studied in this paper. We use the spatial and spectral Fourier transform (F2) method to establish a theoretical-experimental method of describing the relationship between wavelength and mode. This method can directly give out the modal content of optical fibers without any priori parameter such as the properties of fiber and requirement for setup accuracy. On the one hand, the theoretical modeling of wavelength affects modal content. In the simulation, the sources with the same wavelength bandwidth and different central wavelengths are used to test the fiber. The results show that the modal content and number of the fiber change with the wavelength bandwidth and center wavelength. The mode components of the corresponding optical fiber will change after changing the central wavelength. As the spectral width of the light source increases, the number of high-order modes increases. On the other hand, in order to further verify the relationship between wavelength and mode of fiber, the F2 method is used to measure the optical fiber modal content with different wavelengths. The final experimental results are in agreement with the theoretical results. The experimental and simulation results show that the mode field distribution of each mode varies with wavelength: the longer the wavelength, the larger the mode field is. The beam quality has little change with the wavelength except for those positions with frequency near the cutoff frequency, and the power ratio of each mode relates to the wavelength.关键词
光纤模式/基于空间域和频率傅里叶变换的F2法/群时延差异/光谱干涉Key words
fiber modes/F2 method based on spatial and spectral Fourier transform/group delay difference/spectral interference引用本文复制引用
梁井川,冯国英,张澍霖,兰斌,周寿桓..高功率光纤中传输光模式与其波长相关性研究[J].物理学报,2017,66(19):86-94,9.基金项目
国家自然科学基金(批准号: 11574221)和国家高技术研究发展计划(批准号: JG2011105) 资助的课题.Project supported by the National Natural Science Foundation of China (Grant No. 11574221) and the National High Technology Research and Development Program of China (Grant No. JG2011105). （批准号: 11574221）
