NeTS: Small: Modally-multiplexed Spatio-Spectral DispersionCompensation and Routing for Photonic Networks

互联网上的通信流量是由光纤承载的，不断增长的互联网服务需求对光纤通信带宽提出了越来越高的要求。目前的光纤系统已经在一根光纤上使用40个波长通道实现了近100万亿比特每秒的传输。为了进一步提高这一容量，多模光纤中的空分复用(SDM)最近成为下一个研究前沿。SDM允许单个少模光纤每秒传输超过1PB(一千万亿比特)的数据，但当前的SDM系统仅限于少量模式，这是因为在接收器处解开模式所需的数字信号处理的复杂性、成本和功率要求。该项目的研究人员提出了一种革命性的方法，通过一种新颖的全光模式解复用和色散补偿技术，使SDM能够在包含数千个模式的大型纤芯光纤中使用，从而从根本上增加光纤容量。这项技术还可以在物理上分离和光学路由比目前可能的更多的模式，并能够在比任何现有技术更精细的水平上进行光谱过滤。总之，这些发展有可能在多模光纤网络和通信技术方面产生革命性的突破，有可能使互联网光纤主干的带宽和容量至少增加一个数量级。研究人员提出了一种使用相干空间光谱全息图(SSH)的MMF模式解复用和同时模式色散补偿的革命性方法，该方法有可能将模式通道的数量增加100倍，并将可补偿的最大模式延迟增加1000倍。通过在MMF输出场与延迟的平面波参考脉冲(或匹配编码)干涉的情况下曝光，可以在低温冷却的SSH中记录超精细的光谱和角度选择性全息图。当用MMF输出照射时，记录的模式解复用和色散补偿SSH产生光子回波，该光子回波不仅解释了光纤输入处的模式叠加和所有阶次的模式色散，而且还解释了由于光纤缺陷引起的任何模式耦合，并且当光纤被周期性地重新曝光SSH时，这些影响被动态跟踪和补偿。本项目将侧重于实验概念验证，展示使用SSH的MMF空间解复用和色散补偿的可行性，以及该技术的路由和超细谱滤波能力。该项目将与业界合作，评估和确定通过SSH和MMF的组合实现的对光纤网络影响最大的应用程序，以进一步增加下一代互联网主干的带宽、容量和灵活性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The communication traffic on the Internet is carried by optical fibers, and the ever-increasing demand for Internet services is requiring a relentless increase of optical fiber communication bandwidth. Current optical fiber systems have achieved nearly 100 Trillion bits-per-second using 40 wavelength channels on a single fiber. To further increase this capacity, space-division multiplexing (SDM) in multimode fibers (MMF) has recently emerged as the next research frontier. SDM has allowed a single few-mode fiber to carry in excess of a petabit (a quadrillion bits)-per-second but current SDM systems are limited to a small number of modes by the complexity, cost, and power requirements of the digital signal processing needed to disentangle the modes at the receiver. The investigators for this program propose a revolutionary approach to radically increasing fiber capacity by enabling the use of SDM in large core fibers containing thousands of modes via a novel all-optical modal-demultiplexing and dispersion-compensation technique. This technique can also physically separate and optically route many more modes than is currently possible and enables spectral filtering at a much finer level than any existing technology. Together, these developments have the potential to produce a transformative breakthrough in multimode-fiber networking and communication technology with the potential for at least an order of magnitude increase of bandwidth and capacity of the fiber-optic backbone of the Internet.The investigators present a revolutionary approach to MMF modal demultiplexing and simultaneous modal-dispersion compensation using coherent spatial-spectral holograms (SSH) that has the potential to increase the number of modal channels 100-fold and increase the maximum modal delay that can be compensated by 1000-fold. Ultra-fine spectrally- as well as angularly-selective holograms can be recorded in a cryogenically-cooled SSH by exposing with the MMF output field interfered with a time-delayed plane-wave reference pulse (or matched code). When illuminated with the MMF output the recorded modal-demultiplexing and dispersion-compensating SSH produces a photon echo that accounts for not only the modal superposition at the fiber input and modal dispersion to all orders, but also any modal coupling due to fiber imperfections, and these effects are dynamically tracked and compensated as the fiber is perturbed by periodically re-exposing the SSH. This project will focus on experimental proof-of-concept demonstrations of the feasibility of MMF spatial demultiplexing and dispersion compensation using SSH as well as routing and ultrafine spectral filtering capabilities of this technology. This project will engage with industry to evaluate and identify the highest-impact applications to fiber networking enabled by the combination of SSH and MMF to further increase the bandwidth, capacity, and flexibility of a next generation Internet backbone.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.