Design Of Optical Fiber Communication Loss Test System Based On FPGA

With the rapid development of optical fiber communication,the number of optical passive devices has increased rapidly,it has put forward new requirements for the accuracy and efficiency of optical passive device loss testing.A comprehensive parameter test system for optical fiber communication loss based on FPGA design is proposed.It mainly analyzes the stability of optical modules in optical fiber communication and the polarization-dependent loss and return loss of optical node passive components.Specific work includes:First of all,the current status of optical fiber communication loss testing and abroad has been studied to analyze the causes and effects of loss.Aiming at the problem of single test parameters of domestic loss testers,Starting from the theory of light polarization,it studies the changes in the polarization state of light after passing through the polarization device and the measurement methods of the polarization loss and return loss of the optical passive device.Secondly,on the basis of theoretical analysis,use the Optisystem simulation platform to design the optical fiber channel model,and then study the influence of the spectrum change in optical fiber communication and the type of light source and photodetector on the system performance.Through the full polarization scanning method simulation model to understand the settings of the polarization controller parameters,verify the horizontal,vertical,45°linear polarization and circular polarization of the Bonga sphere representation,based on this,an improved full polarization scanning method is proposed.Finally,the test system is designed from two aspects of hardware and software,and the hardware is modularized,including optical modules,two-stage amplification modules,AD acquisition modules,FPGA modules.The key is to solve the problem of weak signal amplification and acquisition.The software is designed through the upper computer and the lower computer,including the configuration of the communication module,the design of the FPGA main program,the AD conversion subroutine,the USB interface configuration program and the design of the upper computer interface.Through the test,the error rate of optical fiber communication is 5.14×10^-13,the output power stability of the optical module is 0.3 d Bm/8h,and the light source stability is good.The polarization-dependent loss and return loss test performance are verified by standard parts,and the polarization-dependent loss value obtained by analyzing the experimental data is more accurate with the longer the test time.