OP: Spatiotemporal Dynamics of Multimode Optical Pulse Propagation: New Route to High-Performance Fiber Lasers

摘要非技术描述：产生极短光脉冲（持续时间为百万分之一秒）的激光器已经开始在组织细胞成像、外科手术、工业材料加工等领域得到应用。这种激光器可以由光纤制成，这很有吸引力，因为光会自动保存在光纤中。迄今为止，用于这种目的的光纤芯非常小（一米的百万分之几），并且只有一种模式或模式的光在光纤中传播。这种模式是大多数人联想到的激光束：一个在其中心最亮的小点。如果光纤的核心变大，其他图案就可以传播。所有允许的模式都重叠，所以出来的光束是它们的复杂混合。光场在光纤中传播时随时间和空间的变化而变化。基于多种模式的激光器理论上可以达到更高的功率，这是应用所需要的，但必须控制模式。对图案的控制也将允许新的功能，例如在新的波长（颜色，包括红外线和紫外线）下产生短光脉冲。在过去的几年里，理论认识和实验技术的进步为研究人员提供了开发基于具有许多重叠图案或模式的光纤的激光器的工具。康奈尔大学和中佛罗里达大学的研究小组将致力于开发基于这种光纤的激光器和其他短光脉冲源。参与该项目的研究生将接受理论和实践训练，为从事科学技术领域的各种职业做好准备。为了增加对科学的接触，增强参与者的多样性，康奈尔大学小组将与4H组织合作，提供旨在让初中生接触科学和可能的职业的讲习班。技术描述：康奈尔大学的一个研究小组将对支持多种电磁场横向模式的光纤中超短光脉冲的传播进行理论和实验研究。由于近年来对多模脉冲传播的理解有了新的进展，基于多模光纤的超短脉冲光源的设计已经成为可能。高功率激光器和宽可调谐强红外脉冲源将被构建和研究。中佛罗里达大学的合作者将提供计算支持。超快科学领域主要建立在基于腔的单一横向模式的短脉冲激光器或支持单一横向模式的光纤上。利用时空波传播来设计新的超短脉冲源以前还没有被考虑过。新的脉冲成形机制将被研究，为高能和超短脉冲提供增强或全新的能力。光纤为研究新的非线性波提供了理想的环境。在提议的工作中获得的知识将与基于模分多路复用的未来电信系统相关。本项目研究的非线性动力学将对应于各种系统中的相关效应，如玻色-爱因斯坦凝聚，多模传播将与湍流的光学研究相关。

Title: High-Performance Lasers Based on Optical Fibers that Allow Many Overlapping Light ModesAbstractNontechnical Description:Lasers that produce very short pulses of light (millionths of millionths of seconds in duration) have begun to find applications that range from imaging of cells in tissue to surgery, to industrial material processing, as examples. Such a laser can be made of optical fiber, which is attractive because the light is automatically kept inside the fiber. In fibers used for this purpose to date, the core of the fiber is very small (a few millionths of a meter) and only a single mode, or pattern, of the light propagates in the fiber. This mode is what most people associate with a laser beam: a small spot that is brightest in its center. If the core of the fiber is made larger, other patterns can propagate. All of the allowed patterns overlap, so the beam that comes out is a complicated mix of them. The light field varies in space and in time as it propagates in the fiber. Lasers based on multiple patterns can theoretically reach much higher powers, which are needed for applications, but the patterns must be controlled. Control of the patterns will also allow new capabilities, such as the generation of short light pulses at new wavelengths (colors, including infrared and ultraviolet). Advances in theoretical understanding and experimental techniques in the last few years now give researchers the tools to develop lasers based on fibers with many overlapping patterns or modes. Groups from Cornell University and the University of Central Florida will work to develop lasers and other sources of short light pulses based on such fibers. Graduate students who work on this project will receive theoretical and practical training, and will be prepared for diverse careers in science and technology. In an effort to increase exposure of science and enhance diversity of participants, the Cornell group will work with the 4H organization to offer workshops aimed at exposing junior-high-school students to science and possible careers. Technical Description:A group from Cornell University will perform theoretical and experimental studies of the propagation of ultrashort light pulses in optical fibers that support many transverse modes of the electromagnetic field. As a result of recent advances in understanding of multimode pulse propagation, which is inherently spatiotemporal in nature, it is now feasible to begin to design sources of ultrashort light pulses based on multimode fiber. High-power lasers, and sources of broadly-tunable intense infrared pulses will be constructed and studied. Collaborators from the University of Central Florida will provide computational support.The field of ultrafast science has been built largely with short-pulse lasers based on a single transverse mode of a cavity, or optical fibers that support a single transverse mode. Exploitation of spatiotemporal wave propagation for the design of new sources of ultrashort pulses has not been considered previously. The new pulse-shaping mechanisms that will be investigated offer enhanced or completely-new capabilities for high-energy and ultrashort pulses. Optical fiber offers an ideal setting to study new nonlinear waves. Knowledge gained in the proposed effort will be pertinent to future telecommunications systems based on mode-division multiplexing. The nonlinear dynamics investigated in this project will correspond to related effects in a variety of systems, such as Bose-Einstein condensates, and multimode propagation will be relevant to optical studies of turbulence.