Development Of A Prototype Of Chromatic Dispersion Measuring Instrument

The construction of broadband infrastructure in China has promoted the development of emerging industries.At the same time,the development of emerging industries has put forward higher requirements for the construction of broadband infrastructure.As one of the infrastructures of the information and communication industry,optical communication technology supports China's social informatization and broadband construction.It is believed that it will occupy a position in the strategy of building a strong network country.Facing the huge opportunities and challenges of optical communication development,the development trend of the next generation high-speed optical fiber communication system is proposed.Dispersion is an inherent property of fiber optic communication system,and the impact on system performance cannot be ignored.Chromatic dispersion measurement has great social value.It is not only applied in the detection of optical fiber manufacturer,but also reflected in the online monitoring of optical fiber link by network operators and the detection of chromatic dispersion in Internet company data center interconnected optical communication networ-k.At present,for the chromatic dispersion measuring instrument,only a few foreign companies can produce it,and the domestic production of such instruments is still in a blank state.Domestic research in this field mainly focuses on tracking foreign technology.Compared with the product series of foreign companies,domestic research in related fields has a theoretical basis,but there is still a big gap in product planning and product development.The development of the home-made produced chromatic dispersion measuring instrument prototype conforms to the "Made in China 2025" strategy put forward by China,and focuses on the new generation information technology industry,with broad prospects for future development.This paper mainly completes the development of the prototype of chr-omatic dispersion measuring instrument.The main work and innovations completed include the following contents;(1)Combining the design requirements of the prototype,the chromatic dispersion measurement methods of the four international standards of phase-shift method,differential phase-shift method,interferometry and optical pulse delay method were compared and analyzed.Finally,the phase-shift method was selected to design prototype.(2)Based on the theory of phase-shift method for measuring chromatic dispersion of optical fibers,selected the appropriate instruments and equipment to complete the construction of the laboratory chromatic dispersion measurement platform.In the data processing part,the phase tracking was completed,the periodic multi-valued condition was effectively recognized,and the phase fuzzy problem was solved.The fitting results of the PSO algorithm and the least squares algorithm were compared.and the least square method was selected to complete the fitting of the dispersion coefficient curve.Finally,the test results of the measurement platform were analyzed,and the feasibility of the phase-shift method for measuring the chromatic dispersion of the tiber was verified.(3)In order to facilitate future debugging,maintenance,function upgrade and expansion of the prototype,modular design mode was selected to complete the design of laser plug-in board,external modulator plug-in board,radio frequency plug-in board,DSP(digital signal processing)plug-in board and power plug-in board.It solved the problems of difficult control of laser signal output by DSP,unstable offset point of external modulator,unstable output of sinusoidal signal.At the same time,the power supply voltage required for each module was large.The centralized management of the voltage was also designed.The final dispersion result value was transmitted to the industrial computer,and the industrial computer adopted LabVIEW to complete the design of the upper computer interface.Finally,for the whole prototype,the experimental verification was carried out and the analysis of the prototype error was completed from the perspective of qualitative and quantitative.The results show that the measured values of the prototype are obviously better than those of the experimental system based on phase-shift method,and the overall results are similar to those of the commercial chromaticity dispersion measuring instrument EXFO FTB-5700.