Research On Key Technologies Of Volume Bragg Grating Dense Wavelength Division Multiplexer

Communication system is one of the important infrastructures of the country.In recent years,with the popularization of smart devices,people's consumption of network traffic has been growing explosion-like.The advent of 5G era has put forward higher requirements for the construction of communication network.In order to increase the communication capacity of the existing optical fiber system,optical wavelength division multiplexing(WDM)technology has been developed continuously,which has solved the current broadband demand well.Several kinds of existing optical wavelength division multiplexers have their own defects,the most important is that the stability is generally not enough,can not be used in the complex work environment.The body Bragg grating based on photo-thermal-refractive glass has excellent filtering performance and strong temperature stability,chemical stability and structural stability,which provides a new idea for the design of WDM system and has great potential in the future.This article combines coupled wave theory and analyzes the diffraction characteristics of volume Bragg gratings in the application scenario of WDM.The main research is the diffraction efficiency,channel spacing,polarization loss,and the relationship between channel crosstalk and grating parameters.The photo-refractive glass was prepared by the secondary chemical method,and the volume Bragg grating was prepared by the dual-beam interference method and the "five-step" thermal fixing process.The errors in the manufacturing process were analyzed,and the fringe drift process and the crystallization growth process were simulated.The influence of performance;given the performance test method of grating,mainly introduced the use of spectrometer test period and grating vector tilt angle,and the use of diffraction efficiency and wavelength selectivity to measure refractive index modulation and other performance parameters.Design experiments were conducted to study the crystallization mechanism of photothermally-refractive glass.The ion migration process and NaF crystallization process were directly detected by Raman spectroscopy and scanning electron microscopy.The diffraction effects of doped and undoped KBr two-component glass and The transmittance spectra were compared to determine that the colloid formed inside the nucleation process was a composite of silver bromide and nano-silver.The colloid aggregated and grew into micelles,which induced the precipitation and growth of NaF crystals on its surface to achieve refractive index modulation.Based on the preparation process,the key parameters that affect the size of the crystallized particles are analyzed,and the methods to improve the modulation degree of the refractive index and the diffraction efficiency of the grating are explored.According to the requirements of 100GHz and 50GHz dense wavelength division multiplexers,combined with the existing grating preparation technology,corresponding applicable transmission and reflection volume Bragg gratings were designed respectively.The performance parameters were theoretically analyzed,and the gratings were completed.Preparation,and finally introduced the design ideas of related schemes of DWDM technology.