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

互联网上的通信流量由光纤承载，不断增长的互联网业务需求要求光纤通信带宽不断增加。目前的光纤系统在一根光纤上使用40个波长通道，达到每秒近100万亿比特。为了进一步提高这种容量，多模光纤（MMF）中的空分复用（SDM）最近成为下一个研究前沿。SDM允许单个单模光纤传输超过1千兆比特/秒，但是目前的SDM系统由于复杂性、成本和在接收器上解开模式所需的数字信号处理的功率要求而局限于少量模式。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态解复用和色散补偿技术，在包含数千个模式的大芯光纤中使用SDM，从而从根本上增加光纤容量。该技术还可以在物理上分离和光路由比目前可能的更多的模式，并实现比任何现有技术更精细的光谱滤波。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变革性突破，并有可能使互联网光纤骨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革命性的MMF模态解复用和同时模态色散补偿方法，该方法使用相干空间光谱全息图（SSH），有可能将模态信道数量增加100倍，并将可补偿的最大模态延迟增加1000倍。通过将MMF输出场与延时平面波参考脉冲（或匹配码）相干扰，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，记录的模态解复用和色散补偿SSH产生光子回波，该回波不仅考虑了光纤输入端的模态叠加和所有阶的模态色散，还考虑了由于光纤缺陷引起的任何模态耦合，并且随着光纤周期性地重新暴露SSH而受到扰动，这些影响被动态跟踪和补偿。该项目将重点进行MMF空间解复用和色散补偿可行性的实验概念验证演示，使用SSH以及该技术的路由和超细频谱滤波功能。该项目将与业界合作，评估和确定通过SSH和MMF组合实现的光纤网络中影响最大的应用，以进一步增加下一代互联网骨干网的带宽、容量和灵活性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.