【作者】 杨毅；

【导师】 付松年；

【作者基本信息】 华中科技大学 ， 光学工程， 2020， 博士

【摘要】 随着新一代移动通信网络的升级和新一轮信息技术的迅猛发展,信息化促使人类生活方式和社会体系发生深刻变革,全球光纤传送网的数据承载能力不断提升,研究新型超大容量信息传输技术已经成为未来光纤通信发展的必然趋势。受限于非线性香农效应,传统单模光纤的通信容量已经逼近其极限,光信号在波长、偏振、时间等方面的复用潜能已被充分挖掘,光信号空间维度作为最后一个可复用维度,空分复用技术一致被认为是满足未来光纤通信容量持续增长的必然选择。论文面向空分复用光纤的偏振保持特性开展研究,重点探索了熊猫型椭圆芯保偏少模光纤设计制备及性能测试,熊猫型保偏四芯光纤设计及性能评估,以及全光纤广义圆柱矢量光束产生。论文的主要研究成果包括:（1）完成支持LP_01x,LP_01y,LP_11ax,LP_11ay,LP_11bx和LP_11by 6个导模熊猫型椭圆芯少模光纤设计与制备,在C+L波段范围内,导模间最小有效折射率差大于1.92×10^-4,相对于传统圆芯光纤,空间和偏振简并性已被完全消除。设计光纤扭转实验方案对所有导模的偏振保持特性分别开展实验测试,在扭转率不大于1.5rad/m的条件下,所有导模的模斑相关系数均大于90%,偏振消光比大于20dB。（2）完成熊猫型保偏四芯单模光纤设计,相比于传统熊猫型保偏单模光纤,可节约应力区50%的材料使用,降低光纤制备成本。使用数值方法评估光纤在1288-1630nm的波长范围内的光学性能:其芯间串扰优于-40dB/100km,每纤芯双折射大于3×10^-4。在光学性能参数如色散、色散斜率、有效模场直径与标准单模光纤相类似的条件下,可满足保偏应用需求。（3）理论发现对叠加合成圆柱矢量光束的两个HG模式进行偏振旋转或模场强度分布旋转操作,可以产生广义圆柱矢量光束。基于保偏少模光纤提出全光纤广义圆柱矢量光束产生装置,研制全光纤偏振控制器,实现HG模场无失真条件下的偏振操控。搭建全光纤装置,验证了理论的可行性。C波段实测结果表明,两种全光纤模场操控方案所产生的广义圆柱矢量光束质量没有差异。更多还原

【Abstract】 Due to the deployment of new generation mobile communication network and the fast development of information communication technology（ICT）,both human lifestyle and social management have been profoundly promoted.In order to improve the transmission capacity of global fiber optical network,the motivation of exploring new ultra-large information transmission technique has become worldwide research topic for future fiber optical communications.Because of nonlinear Shannon effect,the transmission capacity of standard single-mode fiber（SSMF）is approaching its capacity limit.Since the potential multiplexing dimensions of optical signal in terms of wavelength,polarization,and time have been comprehensive investigated.As the last possible multiplexing dimension of optical signal,space division multiplexing（SDM）technique is widely believed as a sustainable solution to satisfy the ever-growing demand of fiber optical transmission capacity.My Dissertation is focused on the polarization maintaining characteristics of SDM fibers and its application,including the design fabrication and characterization of PANDA-type elliptical core polarization-maintaining few-mode fiber（FMF）,design and numerically evaluation of PANDA-type polarization-maintaining four-core fibers,and all-fiber flexible generation of generalized cylinder vector beams（CVBs）.The main research outcomes of Dissertation are summarized as follows:（1）We design and fabricate PANDA-type elliptical-core FMF supporting 6 guided modes,including LP_01x,LP_01y,LP_11ax,LP_11ay,LP_11bx,and LP_11by.The minimum effective refractive index difference among the guided eigenmodes is more than 3×10^-4 over C+L band.Consequently,both spatial and polarization degeneracy arising in the FMF is completely mitigated.Meanwhile,we experimentally carry out evaluation of polarization maintaining characteristics for all guided modes,by twisting the fabricated FMF.When the twisting rate is no more than 1.5 rad/m,the correlation coefficients of all captured mode profiles of all eigenmodes are more than 90%,and the corresponding polarization extinction ratio is more than 20dB.（2）We design the Panda-type four-core single mode fiber.In comparison with traditional Panda-type polarization-maintaining single mode fiber,we can save half of the stress rods,indicating of the reduction of fiber fabrication cost.Our numerical results indicate that the crosstalk between adjacent cores is better than-40dB/100km,and the birefringence of individual core is larger than 3×10^-4,over the wavelength range from 1288nm to 1630nm.Such fiber can satisfy the requirement of polarization maintaining applications,while its optical properties,such as chromatic dispersion,chromatic dispersion slope,and mode field area,are comparable with the SSMF.（3）We theoretically find the generation strategy of generalized CVBs by the rotation manipulation of either polarization orientation or mode profile orientation for two superposition HG modes.Then,an all-fiber CVB generation setup is demonstrated,with the help of novel all-fiber polarization controller and fiber rotator,in order to realize either polarization orientation or mode profile orientation rotation manipulation of HG mode without profile distortion.The feasibility of the theory is verified by the implementation of all fiber setup.Our experimental characterization results verify that there occurs almost no performance penalty over the C-band between two all-fiber rotation manipulation methods.更多还原