基于注入锁定载波恢复的同源相干光传输技术  

Coherent Optical⁃Transmission Technology Based on Optical⁃Injection⁃Locking Carrier Recovery

作　　者：李琨 章明明 李伟昊 周紫文 严思琦 唐明[1] Li Kun;Zhang Mingming;Li Weihao;Zhou Ziwen;Yan Siqi;Tang Ming(School of Optical and Electronic Information&Wuhan National Laboratory for Optoelectronics,Optics Valley Laboratory,Huazhong University of Science and Technology,Wuhan 430074,Hubei,China)

机构地区：[1]华中科技大学光学与电子信息学院,武汉光电国家研究中心,光谷实验室,湖北武汉430074

出　　处：《中国激光》2024年第14期182-190,共9页Chinese Journal of Lasers

基　　金：国家杰出青年科学基金(62225110);国家自然科学基金重点项目(61931010);2023年湖北省重大攻关项目(JD)(2023BAA001-1)。

摘　　要：为了解决传统异源相干探测方案成本较高、数字信号处理算法复杂的问题,同源自零差相干探测方案被视为较有潜力的解决方案之一。同源自零差相干探测系统在信号传输的同时也传输一个同源的直流导频光,作为本振(LO)。但是该方案中本振光在链路中传输存在功率损耗的问题,降低了相干接收灵敏度,限制了传输距离。利用光注入锁定(OIL)则能够在保持频率与相位锁定的同时,有效提高接收端LO光功率,从而解决功率衰落问题。然而链路中偏振态(SOP)的随机变化可能导致OIL长时间处于0功率注入并影响其锁定状态稳定性。在OIL之前引入主动偏振加扰,能够避免潜在的长时间注入光功率过低的情况发生,因此抵抗了偏振衰落。通过理论与仿真研究,揭示了主动偏振加扰对OIL系统锁定/失锁特性的影响,拟合了主动偏振加扰频率与OIL最小失锁阈值功率之间的关系,并开展了大容量的同源自零差相干探测系统传输实验验证。结果表明,OIL能为LO在窄带宽内提供高增益,显著提高信噪比,且外加主动偏振加扰能使OIL系统更容易锁定,在同源自零差相干探测系统中能保持较高灵敏度的相干探测效果。这种方案能有效抵抗光传输过程中的各种衰落,对于偏振衰落问题提供了一种可以解决的方案。Objective In the big-data era, owing to the promotion of explosive digital applications such as artificial intelligence(AI), cloud computing, virtual reality/augmented reality(VR/AR), and data centers, network traffic has increased continuously, thus placing higher requirements on optical-fiber communication systems. In this context, because of concerns such as bandwidth and cost, the conventional coherent optical communication technology is no longer advantageous for supporting industrialized short-distance transmission. Additionally, owing to frequency-selective fading caused by low sensitivity and dispersion, the conventional intensity modulation direct detection(IMDD) technology commonly used for short distances cannot continue to cooperate with the further upgrading and evolution of next-generation communication. Simultaneously, the increase in data-center traffic has become the main component of the global Internet Protocol(IP) traffic. For short-distance coherent optical communication, the self-homodyne coherent detection(SHCD) system significantly reduces the system complexity, cost, and power consumption compared with conventional coherent optical communication systems. It is considered the most promising solution in data centers but still presents the issues of power and polarization fading. In this study, we use optical injection locking(OIL) to overcome power fading and introduce active polarization scrambling(APS) prior to OIL, which can avoid the potential occurrence of long-term, low-optical-power injection and thus prevent polarization fading. This approach facilitates OIL and maintains a highly sensitive coherent detection effect in the SHCD system.Methods First, a numerical model was established for theoretical and simulation analyses. During the simulation, we simulated the frequency change of the injected light amplitude prior to OIL to replace the external APS and then analyzed the effect of APS on the OIL. We discuss the locking characteristics under different injected light-amplitude variat

关 键 词：光注入锁定 主动偏振加扰 抗衰落 同源自零差相干探测系统 

分 类 号：TN209[电子电信—物理电子学]