Wideband Optical Communication Systems Using Phase-Sensitive/Insensitive Fibre Optical Parametric Amplifiers

随着通信服务应用在数量上（如Twitter、YouTube、Facebook等）和带宽上（如HDTV、3D等）的不断增长，承载这些流量的通信系统的所有部分都必须能够以越来越高的速度运行。这种不断增长的容量需求只能通过不断升级网络所有部分的容量来处理，包括主要城市之间的长途链路，以及在客户场所或附近结束的“最后一英里”配电网络。作为光通信系统物理层升级的一部分，在高容量波分复用（WDM）系统中提供更多光带宽以容纳更多单个波长载波的压力越来越大。目前类型的光放大器，即掺铒光纤放大器（edfa）是在20世纪90年代初推出的，但其固定带宽为35 nm，覆盖所谓的c波段（1530-1565 nm）。这种带宽正在迅速耗尽，因此需要引入具有更大带宽的新型光放大器。此外，还有一种趋势是使用高频谱效率的调制格式（例如正交调幅，或QAM）。然而，这种格式需要高的光信噪比（OSNRs）。我们建议研究光纤参量放大器（OPAs）在宽带光通信系统中放大WDM光通信信号的适用性。我们将研究相不敏感OPAs （PIAs）和相敏感OPAs （psa）。后者特别有吸引力，因为它们具有无噪声放大的潜力，这是edfa或相不敏感opa无法实现的。该项目将分为三个阶段，目标如下：第一阶段（12个月）。我们将首先演示具有与edfa相匹配的光带宽的相位不敏感OPAs （PIAs）。这些将在一个循环回路中进行测试，在一个完全填充的WDM信号频谱中，模拟在长途系统中的传播。只使用信号；在每次OPA后，将丢弃惰轮。预计该系统的覆盖范围将达到几千公里。将测试不同的调制格式，波特率最高可达43.7 Gb/s。总吞吐量将达到每秒几太比特。第二阶段（12个月）。然后，我们将在循环回路中交替使用信号和空闲程序。这将使我们能够利用opa的波长转换/相位共轭方面来对抗色散以及一些非线性效应。测试将以更高的聚合速率在更广的全覆盖CWDM频谱上进行。第三期（12个月）。我们将使用相敏opa (psa)，它具有无损放大的潜力，从而增加系统的覆盖范围。我们将研究沿主要极化状态传播的适用性，以维持信号、闲散器和泵的极化状态，这是最佳PSA操作所必需的。如果该项目成功，它将证明光纤opa确实是一个潜在的竞争者，可以提供超过edfa波长范围的光学放大，并且以几乎无噪声的方式，与长途或分配光通信网络兼容。因此，它们原则上可以为未来的高容量光网络提供下一代光放大器。

As communication services applications continue to grow in number (e.g. Twitter, YouTube, Facebook, etc.) and in bandwidth (e.g. HDTV, 3D,...), all parts of the communication systems carrying this traffic must be able to operate at higher and higher speeds. This ever-growing capacity demand can only be handled by continually upgrading the capacity of all parts of the network, including long-haul links between major cities, as well as the 'last mile' distribution networks ending at or near the customer premises. As part of this upgrading of the physical layer of optical communication systems, there is increasing pressure to provide more optical bandwidth to accommodate more individual wavelength carriers in high-capacity wavelength-division multiplexed (WDM) systems. The current type of optical amplifiers, namely Erbium-doped fibre amplifiers (EDFAs) were introduced in the early 1990s, but have a fixed bandwidth of the order of 35 nm, covering the so-called C-band (1530-1565 nm). This bandwidth is being rapidly exhausted, and so there is a need for introducing novel optical amplifiers with substantially larger bandwidth. In addition, there is also a trend toward using high-spectral efficiency modulation formats (e.g. quadrature amplitude modulation, or QAM). However, such formats require high optical signal to noise ratios (OSNRs). We propose to investigate the suitability of fibre optical parametric amplifiers (OPAs) to amplify WDM optical communication signals in wideband optical communication systems. We will investigate both phase-insensitive OPAs (PIAs) and phase-sensitive OPAs (PSAs).The latter are particularly attractive because of their potential for noiseless amplification, which cannot be achieved with EDFAs or phase-insensitive OPAs.The project will consist of three phases with the following objectives:Phase I (12 months). We will first demonstrate phase-insensitive OPAs (PIAs) with an optical bandwidth matching that of EDFAs. These will be tested in a recirculating loop, with a fully-populated WDM signal spectrum, simulating propagation in a long-haul system. Only the signals will be used; the idlers will be discarded after each OPA. It is expected that the reach of the system will be several thousand kilometres. Different modulation formats will be tested, with baud rates up to 43.7 Gb/s. Aggregate throughput will reach several terabits per second.Phase II (12 months). We will then use signals and idlers in an alternating manner in the recirculating loop. This will allow us to exploit the wavelength conversion/phase conjugation aspects of OPAs to combat dispersion as well as some nonlinear effects. Testing will be done with a wider fully populated CWDM spectrum, at a higher aggregate rate. Phase III (12 months). We will use phase-sensitive OPAs (PSAs), which have the potential for lossless amplification, leading to an increase in system reach. We will investigate the suitability of propagation along principal states of polarization, in order to maintain the states of polarization of signals, idlers, and pump, necessary for optimum PSA operation.If the project is successful, it will demonstrate that fibre OPAs are indeed a potential contender for providing optical amplification over wavelength ranges exceeding that of EDFAs, and in a nearly noiseless manner, which is compatible with use in either long-haul or distribution optical communication networks. Hence they could in principle provide the next generation of optical amplifiers for future high-capacity optical networks.