GOALI: A comprehensive study of nonlinear phenomena in multimode optical fibers for enhancing the performance of optical communication systems

目的：为了提高光通信系统的性能，对多模光纤中的非线性现象进行综合研究。摘要：光纤用于远距离传输信息使因特网的传播成为可能。在20世纪90年代和2000年代的几十年里，一种名为波分复用的技术的出现帮助提高了基于光纤的通信系统的容量。然而，目前的系统将无法满足在线学习和视频流等活动所推动的数据速率的持续增长。为了满足这一需求，世界各地的实验室正在研究一种名为空分复用(SDM)的新技术。它利用被设计为支持多种空间模式的光纤，通过使用单个大尺寸纤芯或多个较窄的纤芯，每个纤芯支持一个模式。然而，在SDM技术可以在实际系统中实现之前，有必要了解在多模光纤或其纤芯由于接近而耦合的多芯光纤内发生的各种非线性效应的影响。研究的主要目标是开发和实现新的理论和数值工具，用于模拟多芯或多模光纤中多个数据流在SDM中的同时传输。这些工具将用于基本了解在存在各种非线性效应，如自相位调制、交叉相位调制、受激拉曼散射和四波混频的情况下，每个SDM通道如何受到其他同传播通道的影响。尽管理想光纤的模式不应该彼此耦合，但任何现实的多模光纤的模式都会经历一些随机耦合。这个目标项目的一个主要目标是了解这种耦合的起源，并研究它如何影响各种非线性效应和SDM系统的性能。在这项工作中，我们的工业合作伙伴将提供巨大的帮助，因为贝尔实验室最近进行的实验已经量化了六模光纤中随机模耦合的程度。该项目既有基础方面的，也有应用方面的。更好地理解多模光纤中的非线性现象是至关重要的，应该有助于下一代研究生和科学家提出新的器件想法。对非线性效应的研究也将有助于未来SDM系统的设计。作为博士论文的一部分，两名研究生将在这个目标项目上与P.I.合作。他们两人每年都会在工业现场呆上一段时间，以便获得宝贵的工业经验。这种对研究生的培训是培养美国电信业劳动力的理想选择。

Title: GOALI: A comprehensive study of nonlinear phenomena in multimode optical fibers for enhancing the performance of optical communication systemsAbstract:The use of optical fibers for transmitting information over long distances has made the spread of the Internet possible. The advent of a technique, known as wavelength-division multiplexing, helped in increasing the capacity of fiber-based communication systems during the decades of the 1990s and 2000s. However, current systems will not be able to meet the continuing increase in the data rates fueled by such activities as on-line learning and video streaming. A new technique, called space-division multiplexing (SDM), is being studied in the laboratories worldwide to meet this demand. It makes use of optical fibers that are designed to support multiple spatial modes either by using a single large-size core or several narrower cores, each supporting a single mode. However, before the SDM technique can be implemented in real systems, it is necessary to understand the impact of various nonlinear effects occurring inside a multimode fiber, or a multicore fiber whose cores are coupled in view of their close proximity. This is what the proposed research project will accomplish.The main goal of the proposed research is to develop and implement new theoretical and numerical tools for modeling the simultaneous propagation of multiple data streams through SDM inside a multicore or a multimode fiber. These tools will be used to develop a fundamental understanding of how each SDM channel is affected by other co-propagating channels in the presence of various nonlinear effects such as self-phase modulation, cross-phase modulation, stimulated Raman scattering, and four-wave mixing. Even though the modes of an ideal fiber should not be coupled to each other, modes of any realistic multimode fiber will experience some random coupling. A major objective of this GOALI project is to understand the origin of this coupling and study how it impacts various nonlinear effects and the performance of SDM systems. In this effort, our industrial partner would be of immense help because of the recent experiments performed at Bell Labs that have quantified the extent of random mode coupling in six-mode fibers. The project has both the fundamental and applied aspects. An improved understanding of the nonlinear phenomena in multimode fibers is of fundamental importance and should help the next generation of graduate students and scientists in coming up with new device ideas. The study of nonlinear effects should also help in designing the future SDM systems. Two graduate students will work with the P.I. on this GOALI project as a part of their Ph.D. thesis. Both of them will spend time each year at the industrial site so that they can acquire valuable industrial experience. This kind of training of the graduate students is ideal for developing the work force for the U.S. telecommunication industry.