Novel Dispersion-Division-Multiplexing Technique for Enabling Double the Spectral Efficiency in Transmission and Routing of Photonic and Microwave Networks

长期以来，光纤具有无限带宽一直是一个令人舒服的谬论，因此，我们有带宽可以消耗。随着使用波分复用（WDM）的多通道通信的爆炸式增长，可用带宽现在占据了中心位置。当将光通信与其他类型的通信进行比较时，我们在频谱效率（即比特/赫兹）方面远远落后，我们甚至没有接近香农容量极限。事实上，更高的频谱效率可能是该领域最缺乏创造性活动的领域，但它有望在未来的系统容量中实现革命性的增长。在光通信中，显示出带宽浪费最多且具有许多未来潜在应用的技术领域之一是在单个波长载波上的许多低速信道的子载波复用（SCM）。在单片机中，一半的数据带宽被浪费了，因为：(i)传输双向带信号实质上会复制正在发送的数据，因为每个边带都携带接收所需的全部信息，或者（ii）传输单边带信号需要载波另一侧的镜像频率（即，第二个边带将位于的地方）保持未被任何其他数据信号占用。子载波复用对未来的光通信系统有许多优点，包括：(a)在单个高容量波长上传输许多低速数字数据信号，(b)传输许多模拟调制信号，(c)用于容纳基于无线微波的光信号的网络的传输介质，以及(d)在分组交换网络中传输有效路由的控制标签。我们建议实现一种新的复用方案，使使用子载波复用的光学系统的频谱效率提高一倍。该方案被称为色散分多路复用（DDM），它依赖于在远离光载波的同一频率空间中同时放置两个数据通道。例如，按惯例传输一个双边带数据信道，并且在第一信道的阴影下传输第二个双边带信道。阴影的产生是由于光纤的色散。由于频散的原因，单个信道的两个双频段中的每一个将以略有不同的速度传播。这些边带相对于光载波将周期性地相互失相，从而相互抵消并诱导射频功率衰落（即，接收器上给定信道的功率几乎完全消失）。当另一个信道同相且功率满时，一个信道会褪色。通过使用可调谐的色散诱导元件，接收器可以改变每个信道的两个边带之间的相对相位，从而恢复两个频率共位于的信道中的任何一个。我们的研究计划将研究频谱高效色散分复用技术的独特功能、机遇和局限性，该技术可能在5-10年内取得重大成果。我们的系统和网络研究计划的关键基本特征如下。我们将：(a)为许多WDM信道演示高频谱效率的DDM，(b)演示DDM在无线光子网络中互连节点的效用，(c)演示WDM光子网络中的SCM标签交换和路由，以及(d)在考虑信噪比，消光比和数据带宽时研究产生，发送和接收DDM信道的基本限制。目录表

It has long been a comfortable fallacy that the optical fiber has infinite bandwidth, and, therefore,we have bandwidth to burn. With the explosion of multiple-channel communications through the usewavelength-division-multiplexing (WDM), available bandwidth now takes center stage. Whencomparing optical communications with other types of communications, we lag far behind in terms ofspectral efficiency (i.e., bits/Hz) and we are not even close to the Shannon capacity limit. In fact, higherspectral efficiency is probably the area of least creative activity within the field, and yet it holds thepromise for revolutionary increases in future systems capacity. One of the technical areas within optical communications that has shown the most bandwidthwaste and has many future potential applications is subcarrier multiplexing (SCM) of many lower-speedchannels on a single wavelength carrier. In SCM, half the data bandwidth is wasted since either:(i) transmitting double-sideband signals will, in essence, duplicate the data being sent given that eachsideband carries the full information needed for reception, or (ii) transmitting single-sideband signalsrequires that the mirror frequencies on the other side of the carrier wave (i.e., where the second sidebandwould have been located) remain unoccupied by any other data signals. Subcarrier multiplexing has many advantages for future optical communications systems,including: (a) the transmission of many lower-speed digital data signals on a single high-capacitywavelength, (b) the transmission of many analog-modulated signals, (c) the transmission medium fornetworks that accommodate wireless microwave-based optical signals, and (d) the transmission of controllabels for efficient routing in packet-switched networks. We propose implementing a new multiplexing scheme that enables double the spectral efficiencyfor optical systems that use subcarrier multiplexing. The scheme is called dispersion-division-multiplexing(DDM) and relies on placing two data channels simultaneously in the same frequency spaceaway from an optical carrrier. For example, one double-sideband data channel is transmittedconventionally, and a second double-sideband channel is transmitted in the shadow of the firstchannel. Shadowing occurs due to the chromatic dispersion of the optical fiber. Due to dispersion, eachof the two double sidebands of a single channel will travel at slightly different speeds. These sidebandswill periodically be out-of-phase will each other relative to the optical carrier wave, thereby cancelingeach other and inducing RF power fading (i.e., a nearly complete disappearing of the given channel'spower at a receiver). One channel would be faded when the other channel would be in-phase and havefull power. By using a tunable dispersion-inducing element, a receiver can change the relative phasebetween each cannel's two sidebands and thus recover either of the two frequency-co-located channels. Our research program will investigate unique functionalities, opportunities, and limitations whenusing spectrally-efficient dispersion-division-multiplexing that could bear significant fruit in the 5-10year time frame. The key fundamental features of our systems and networking research program are asfollows. We will:(a) demonstrate highly-spectrally-efficient DDM for many WDM channels,(b) demonstrate the utility of DDM for interconnecting nodes in a wireless-based photonicnetwork,(c) demonstrate SCM label swapping and routing in a WDM photonic network, and(d) investigate the fundamental limitations of generating, transmitting, and receiving DDMchannels when considering SNR, extinction ratio, and data bandwidth.TABLE OF CONTENTS