Author Affiliations
Abstract
Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China
We have demonstrated the highly efficient excitation of the linearly polarized mode (LP01) in ring-core fibers (RCFs) by tapering the spliced point between the RCF and the standard single-mode fiber (SMF) to optimize all-fiber orbital angular momentum (OAM) generation. The tapering technique has been investigated theoretically and experimentally. Before tapering, only 50% of light can be coupled from SMFs to RCFs. The modal interference spectrum with an extinction ratio (ER) of ～9 dB is observed, showing that higher-order modes are excited in RCF. By tapering the spliced point, 90% of light is coupled, and the ER is minimized to be ～2 dB, indicating that the higher-order modes are effectively suppressed by tapering. Such tapered spliced points of RCF–SMF are further applied for all-fiber OAM generation. The efficiencies of OAM+1 and OAM?1 generation are found to be enhanced by approximately 11.66% and 12.41%, respectively, showing that the tapered spliced point of the RCF–SMF is a feasible way to optimize OAM generation.
ring-core fiber single-mode fiber all-fiber orbital angular momentum generation tapering technology Chinese Optics Letters
2020, 18(2): 020602
本文采用振荡-放大装置测量了铜蒸气激光5106谱线的增益和饱和能量密度,它们分别为0.2cm~(-1)和22.3μJcm~(-2).并对实验结果进行了讨论.
空间和时间匹配
本文描述一台四灯泵浦平板自波导染料激光器,以30次/秒脉冲重复率运转时平均输出功率达3瓦。利用泵浦脉冲在激活介质内所造成的折射率梯度的非均匀分布形成激光波导腔,充分利用了染料溶液的高增益区,由此获得高效率和高功率输出。
我们研制成了用高速涡流气体产生的压力梯度场来稳定脉冲放电电弧的高功率涡流闪光灯。当工作氩气的流量为5升/秒时,已经实现了工作频率为110次/秒的万瓦放电。放电的峰值电流最大达20千安,放电闪光上升时间为1～1.5微秒,脉宽为3～4微秒,发光效率达30％。本文报告了这种灯的结构,灯的放电电路、灯内压力梯度场的分布、灯的电光特性和灯的功率平衡分析等结果。
研究了用作染料激光器泵浦源的短脉冲氙灯, 闪光脉宽小于2微秒, 光强上升时间小于0.6微秒。在额定负载能量下有效使用寿命大于10~7次。本文主要讨论灯的物理与工艺参数对其负载特性和辐射特性的影响。
