Kwaśny Michał, Mergo Paweł, Napierała Marek, Markiewicz Krzysztof, Laudyn Urszula A
Faculty of Physics, Warsaw University of Technology, 75 Koszykowa, 00-662 Warsaw, Poland.
Laboratory of Optical Fiber Technology, University of Maria Curie-Skłodowska, 3 M. Curie-Skłodowskiej Square, 20-031 Lublin, Poland.
Materials (Basel). 2022 Aug 15;15(16):5604. doi: 10.3390/ma15165604.
Our study investigated the partially degenerate intermodal four-wave mixing (IM-FWM) process in nonlinear multimode optical fibers with strain-induced birefringence. The difference in the refractive index along the two orthogonal directions was due to the photoelastic effect that occurred when the fiber under test (FUT) was subjected to uniformly applied diameter stress caused by winding on a cylinder of a given diameter. Our work analyzed how the nonlinear frequency conversion and the output modal field profiles depended on the degree of birefringence in FUT. The experimental results significantly affected the order of the excited moduli in fiber sections characterized by different amounts of birefringence. We also checked the efficiency of the FWM process for different polarizations of the pump beam to determine those for which the FWM process was most effective for the 532 nm sub-nanosecond pulses. More than 30% conversion efficiency was obtained for the FUTs with a length of tens of centimeters.
我们的研究调查了具有应变诱导双折射的非线性多模光纤中的部分简并多模四波混频（IM-FWM）过程。沿两个正交方向的折射率差异是由于被测光纤（FUT）缠绕在给定直径的圆柱体上而受到均匀施加的直径应力时发生的光弹效应所致。我们的工作分析了非线性频率转换和输出模式场分布如何取决于FUT中的双折射程度。实验结果显著影响了具有不同双折射量的光纤段中激发模式的顺序。我们还检查了泵浦光束不同偏振情况下FWM过程的效率，以确定对于532 nm亚纳秒脉冲而言FWM过程最有效的偏振情况。对于长度为几十厘米的FUT，获得了超过30%的转换效率。
