光纤色散和非线性效应对10Gb/s通信系统的影响研究

Effect of Dispersion and Nonlinearity of Optic Fiber on 10Gb/s Communication Systems

对10Gb/s通信系统传输特性的传输特性进行理论与实验研究,讨论了光纤色散和非线性效应对系统传输特性的影响。利用分步傅里叶变换法对光脉冲在光纤中的传输方程-非线性薛定谔方程进行求解,讨论光纤色散和非线性效应对光脉冲的影响。数值计算表明,光纤色散使脉冲展宽,高阶色散效应引起脉冲前沿形成非对称振荡;非线性效应引起的自相位调制使脉冲形状发生畸变。10Gb/s通信系统传输实验系统由DFB激光器、偏振控制器、调制器、光纤放大器、调谐带通滤波器、数字通信仪、色散补偿器及光谱分析仪组成。当输入信号波长为1550.357nm、功率为4.99dBm、光纤放大器泵浦电流为101.04mA时,信号经过50.4km长距离传输后,其光脉冲不仅展宽了,而且还发生了严重的畸变,系统的传输性能恶化,信号眼图基本闭合,当插入色散参数为D=-647.8ps/(nm.km)的色散补偿器后,信号得到很好补偿。当光纤中同时传输功率为10.0dBm、波长分别为1543.00nm与1543.10nm的10Gb/sRZ光信号时,经50.4km光纤传输后,信号波形发生畸变,存在交叉相位调制。

The transmission performance of 10Gb/s is studied theoretically and experimentally,the effect of dispersion and nonlinearity of optic fiber on 10Gbit/s transmission communication systems is discussed.The propagating equation,Nonlinear Schr dinger Equation(NLSE)of ultrashort pulses in optic fiber are solved by split-step Fourier transform method.Numerical results demonstrate that optic fiber dispersion broadens pulse width,hight-order dispersion can cause an asymmetrical oscillation in front pulse,and self-phase modulation caused by optic fiber nonlinearity makes the profile of pulses aberration.The 10Gb/s transmission system consists of a DFB laser,polarizer controller,modulator,erbium doped fiber amplifier,bandpass tunable filter,dispersion compensator,optical spectrum analyzer,and a digital communication analyzer.For the optical pulse with central wavelength of 1550.357nm and power of 4.99dBm,in the case of EDFA pump current of 101.04mA,its width broadens and shape is serious aberrance after transmission distance is at 50.4km,this deteriorates the performance of transmission system and the eye diagram of signal almost closes.When a dispersion compensator with D=-647.8ps/(nm·km)is inserted in the transmission line,the aberrance signal can be compensated,and the performance of the transmission system is improved.In the case of two WDM wavelength 1543.00nm and 1543.10nm with power of 10.0dBm modulated by 10Gb/s RZ signal,waveforms are serious aberrance after transmission distance is at 50.4km,and cross-phase modulation exists.