【作者】 李培丽；

【导师】 黄德修； 张新亮；

【作者基本信息】 华中科技大学 ， 物理电子学， 2005， 博士

【摘要】 可调谐全光波长转换器是智能化密集波分复用(DWDM)全光通信网络中的关键器件之一。基于半导体光纤环形腔激光器(SFRL)的四波混频(FWM)型可调谐全光波长转换器不仅对信号光的调制格式、调制速率严格透明,能实现多波长转换,而且可以节省了一个外部泵浦光源,简化了装置,利用环行腔中的可调谐光滤波器,可方便地实现可调谐波长转换,因而受到了广泛的关注。本文围绕基于SFRL 的FWM 型可调谐全光波长转换器进行了较为系统的理论和实验研究。具体内容如下: (1)研究了SFRL 用作波长转换器的理论基础,推导了半导体光放大器(SOA)中最基本的光场传输方程和载流子速率方程,讨论了SOA 中的各种非线性效应,尤其是三阶非线性效应;研究了基于SFRL 的交叉增益调制(XGM)型波长转换器和基于SFRL的FWM 型波长转换器的工作机理,并分析了它们的优缺点。(2)给出了基于SFRL 的FWM 型波长转换器的简洁、直观、使用方便的lump 模型,并首次建立了这种波长转换器的完整的宽带理论模型。在宽带理论模型中,对SOA有源区和放大自发辐射(ASE)谱都进行了分段,并且考虑了SOA 的材料增益谱、载流子的空间分布、光场的纵向空间分布和宽带ASE 谱等。宽带理论模型是研究这种可调谐全光波长转换器进行性能分析和优化设计的理论基础。(3)利用建立的基于SFRL 的FWM 型可调谐全光波长转换器宽带理论模型,通过数值模拟的方法,对这种可调谐波长转换器的稳态特性和动态特性进行了深入的理论研究,分析了输入信号光功率、注入电流强度、环形腔中两个耦合器的耦合比、激射波长和SOA 有源区长度对输出特性的影响,还分析了线宽增强因子和限制因子对转换光消光比和啁啾的影响。(4)首次实现了20Gbit/s 的基于SFRL 的FWM 型可调谐波长转换,并且进行了10Gbit/s 的基于SFRL 的FWM 型可调谐波长转换的实验,研究了这种可调谐波长转换器的转换效率和信噪比(SBR)与输入信号光功率、注入电流、环形腔中两个耦合器耦合比和SFRL 激射波长的关系,还研究了输入信号光功率对转换光消光比的影响以更多还原

【Abstract】 Tunable all-optical wavelength converters will be one of the essential devices in future intellectualized dense wavelength-division multiplexed (DWDM) all-optical networks. Tunable wavelength converter based on four-wave mixing (FWM) in semiconductor fiber ring laser (SFRL) has advantages, which are possessed by the wavelength converter based on FWM, such as strict transparency to bit the rate and modulation format of signals, phase conjunction, multiple channels simultaneous conversion ability etc. Furthermore, it possesses the virtues of saving an external pump source to simplify device and expediently being tuned. So many attentions were paid to this kind of wavelength conversion. In this dissertation, theoretical and experimental research on wavelength conversion based on FWM in SFRL is presented. The main contents are as follows: (1) Theoretical basis for wavelength conversion based on SFRL is investigated. The propagation equation for the optical field and the rate equation for the carrier density in semiconductor optical amplifier (SOA) are derived. And the nonlinearities of SOA, especially the third-order nonlinearities, are discussed. The mechanisms of wavelength converters based on across-gain modulation (XGM) in SFRL and wavelength converters based on FWM in SFRL are given. (2) Besides the simple and convenient lump model, the comprehensive broad-band dynamic model of a tunable wavelength conversion based on FWM in a SFRL is presented firstly. In the broad-band dynamic model, SOA and the amplified spontaneous emission (ASE) spectrum are divided into many subsections. Critical factors, e.g., the material gain profile, the longitudinal variation of the optical field, the carrier density, photon density, and the broad-band spontaneous noise emission, are considered in the model. Therefore, the static and dynamic characteristics of this kind of wavelength conversion can be predicted more accurately. This broad-band dynamic model is the theoretical basis of a tunable wavelength converter based on FWM in a SFRL. (3) Using the broad-band dynamic model of tunable wavelength converter based on FWM in a SFRL, the static characteristics and the dynamic characteristics are investigated by numerical simulation, such as the conversion efficiency, signal-to-background-noise ratio (SBR), the extinction ratio, and the frequency chirp of the conjugate signal. And some of contributing factors including the input signal power, injection current, coupling coefficient of the two couplers, the lasing wavelength, and the length of SOA are analyzed. Also the effects of the linewidth enhancement factor and the limiting factor on the extinction ratio and the frequency chirp of the conjugate signal are studied. (4) 20Gbit/s tunable wavelength conversion based on FWM in a SFRL is experimentally demonstrated firstly. Tunable wavelength conversion based on FWM in a SFRL is experimentally investigated at 10Gbit/s. The effects of the input signal power, injection current, the coupling coefficient of the two couplers, and the lasing wavelength on the conversion efficiency and SBR of this kind of wavelength converter, as well as the effects of the input signal power on the extinction ratio of the conjugate signal are investigated. (5) New scheme for FWM wavelength converter based on single-port-coupled SFRL is brought forward firstly. Theoretical and experimental investigations are investigated. Theoretical analysis shows that high conversion efficiency and high SBR can be achieved by using this scheme if the proper reflectivity of the rear facet of SOA is selected. (6) Improved scheme for FWM wavelength conversion based on double output wavelength SFRL with an assisted beam is put forward. Theoretical analysis shows that polarization-free, high conversion efficiency and high SBR in wide wavelength range can be achieved by using this scheme. Also the broad-band dynamic model of this kind of wavelength conversion is presented.更多还原