圆环阵列多芯双包层激光相干合束的研究

Coherent laser beam combination by use of dual-cladding multi-core optical fiber ring array

由于受到纤芯面积、非线性效应等因素的限制,单芯光纤激光器的输出功率极限值为千瓦级。欲获得上百千瓦和兆瓦级的输出功率,必须借助合束技术。多芯双包层光纤激光相干合束法以其实验装置简单、自组织相干不需外界调制、泵浦光耦合效率高、纤芯阵列排列灵活等特点成为相干组束技术中一种比较有前途的方案。基于衍射理论推导出多芯双包层光纤激光器的远场相干光光强理论模型,在此基础之上,分析了纤芯数目、相邻纤芯轴间距离、纤芯直径、波长对合束的影响。分析结果表明:通过增加纤芯数目、减小纤芯间距离、在保证单模特性的前提下增大纤芯芯径可以有效提高合束效果,研究结果为优化相干合束方案、研制出高性能的多芯合束双包层光纤提供了参考。

The maximum output power of an optical fiber laser using conventional single core fiber is only several kilowatts due to the nonlinear effect in fiber and the limited cross -section of fiber core.The combination of laser beams is an efficient approach to increasing its output power up to hundreds of kilowatts and megawatts.Among current various combination schemes,the scheme of coherent beam combination by using dual-cladding multi-core fiber is most promising because of its simplicity in experiment equipment,free of external modulation,high coupling efficiency of pump light,and flexible core array.Based on light diffraction theory,a far-field distribution equation for the coherent beam intensity of the dual -cladding multi -core fiber laser was derived.Numerical analysis demonstrate that the quality of combined laser beam can be efficiently improved by increasing the number of fiber cores,decreasing the axial interval between cores,and enlarging core diameter.The above work is helpful to the optimization of coherent beam combination scheme and the fabrication of dual-cladding multi-core optical fiber.