3阶色散对相位整形不归零码传输性能的影响

为了研究3阶色散对相位整形不归零(phase-shaped nonreturn-to-zero,PSNRZ)码传输性能的影响,通过仿真对带有初始啁啾的高斯脉冲受3阶色散影响的情况进行了研究。研究发现,初始啁啾的存在会严重加剧3阶色散对波形演化的影响。而通过对PSNRZ码传输性能的仿真进一步发现,与3阶色散补偿后相比,未补偿时的传输距离受到很大限制,当链路残余色散低于20ps/nm时,最大传输距离减小超过500km。结果表明,当采用PSNRZ码通信时,必须对3阶色散进行补偿。

Automatic acquiring and analyzing system of laser spot based on virtual instruments

In order to acquire laser beam parameters, provide information for designing and improving the laser, an automatic acquiring and analyzing system of laser spot was established and an experiment platform was built up. Software used for acquiring and analyzing laser spot was programmed based on LabVIEW, a virtual instrument platform, and its image processing toolbox called NI Vision. This software can display the trail of the laser spot center, concluding the standard deviations and the temporal trend of both the x-axis drift and y-axis drift. Furthermore, it can be used to analyze the fundamental mode of the laser beam. An image of laser spot can be displayed in the form of 3-D gray graph after noise removing. The data at any section of the 3-D gray graph can be acquired and used for Gaussian curve fitting, concluding the fitting parameters in order to judge how much the actual laser beam is close to a theoretical Gaussian one. Results indicate that this system can dynamically acquire and process information of the laser spot at real time.