【作者】 李源；

【导师】 杨克成；

【作者基本信息】 华中科技大学 ， 物理电子学， 2010， 博士

【摘要】 近几年来超大容量、超长距离密集波分复用技术发展十分迅猛,目前单个波长传输速率已达40Gb／s或者100Gb／s,单根光纤容量已超过3.2Tb／s。在如此高速率的光传输中,必然招致巨大的传输损伤,这些传输损伤主要有三类,有光放大器的放大自发辐射噪声、色散包括群速度色散和偏振模色散,非线性效应包括自相位调制、交叉相位调制、受激拉曼散射、受激布里渊散射和四波混频等。为了进行高速光纤通信必须克服这些传输损伤。本论文基于全光时域傅立叶变换(OIFT/OFT:(Inverse)Optical Fourier Transformation)和分数阶傅立叶变换(FRFT:Fractional Fourier Transformation)的方法研究了高速光纤通信中色散补偿和噪声抑制的新方法和原理。本论文首先通过研究光脉冲传输的薛定厄方程,并结合光波的时间-空间二元性的映射理论,设计出了全光时域傅立叶变换器件——时间透镜(time lens),并基于时间透镜提出一种新型的应用于单波长传输速率100Gb／s以上的高速光纤频域传输技术和系统——光频域传输方法(OFTS:Optical Frequency Domain Transmission).利用光脉冲在线性光纤中传输时,其频谱包络不变的原理,通过在光纤通信系统的发射端和接收端各加入一个全光傅立叶正、反变换器件来实现无偏振模PMD补偿无色散斜率补偿的100Gb／s以上速率的低成本长途光传输。可用于目前10Gb／s光纤传输系统的直接升级。论文完成了OFTS传输技术的模型并仿真和通过实验来验证系统的性能。最终实现了20Gb／s传输200公里无任何色散补偿,误码率达到10-9。本论文还基于时间透镜和分数阶傅立叶变换的原理设计出一种带内噪声的滤波系统和装置,通过采用将信号和噪声通过分数阶傅立叶变换分别变换到不同的域,然后,在接收端进行信号和噪声的分离,通过仿真分析了系统的性能,结果表明,该系统可以提高信噪比6dB。更多还原

【Abstract】 With the explosive development of ultra-capability, ultra-distance DWDM technologies, recently the transmission speed has been 40 Gbit/s per channel, even 100 Gbit/s, over a long distance, and the capability per fiber has been 3.2 Tbit/s, which will lead to serious impairments to the system performance. These impairments are:ASE noises caused by the EDFAs; chromatic dispersion (Group Velocity Dispersion (GVD) and polarization mode dispersion (PMD)); nonlinear effects, which contain self phase modulation (SPM), cross phase modulation (XPM), four-wave mixing (FWM), stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS). All these impairments should be overcome in high-speed optical communications.In this thesis, we present new methods and theories of dispersion compensation and noise suppression based on all-optical inverse Fourier transform/Fourier transform (OIFT/OFT) and fractional Fourier transform (FRFT).We begin with nonlinear Schrodinger equation (NLSE) and time-space duality, the OIFT/OFT device based on time lens is implemented. Here time lens is simply a quadratic phase modulation. As we know, the spectrum envelop of signal will keep unchanged during linear transmission. Thus a novel transmission method-optical frequency domain transmission based on time lens is proposed which could be used in high-speed optical transmission, over 100 Gbit/s per channel. At the transmitter, the OIFT device, which consists of the first time lens and two high dispersive elements, is used to transform the initial optical pulses. The OFT, consisting of the second time lens and another two high dispersive elements, rebuilds the initial optical pulses at the receiver. The system containing OIFT/OFT can propagate over a long haul distance without PMD compensation and with a very low cost. Another advantage is that the OIFT/OFT device could be used in the existed 10 Gbit/s system directly. Our OIFT/OFT-based system successfully transmits through 200-km G.655 fibers at the speed of 20 Gbit/s without any dispersion compensation, with the BER being 10-12.Furthermore, an in-band noise filter is designed based on the principle of FRFT and time lens. The signals and noises are transformed into another domain using FRFT method. Then we could separate the signals and noises at the receiver. We also analyze the system performance through the simulations and the results show that there is 6-dB improvement of signal-to-noise ratio (SNR) using this in-band noise filter.更多还原