Study On The Preparation Of Germanium Core Fiber By Melt Core Method And Modification By Post Heat Treatment

Germanium core fiber with transparent to infrared light,high Raman gain,high nonlinearity and other excellent characteristics has great potential application in infrared transmission and sensing,Raman fiber devices,terahertz optical waveguide in the aspects of broadband,which is a hot topic in the field of optical fiber technology.In the future,the core devices,such as modulators and detectors made of germanium core fiber,will play an important role in military,aerospace,high energy physics,biomedicine and other fields.Firstly,the preparation of Germanium core optical fiber by molten core method was introduced.The test methods used in the process of experiments including scanning electron microscopy and energy dispersive spectroscopy,Raman spectra and X-ray diffraction spectrum are introduced.Secondly,two kinds of methods are used to heat the germanium core fiber,One of the heating temperature is below the melting point of germanium and the other is higher than the melting point of germanium.The study found that,compared with unannealed fiber,the Raman peaks of the fiber annealed at 900?shifted to high wavenumber at 2.9 cm^-1,and the FWHM decreases 0.22 cm^-1.It is indicated that900?is a suitable annealing temperature in low temperature annealing.Furtherly,We improve the heat treatment temperature to 1000?to study the effect of recrystallization on the germanium core fiber,which is higher than the melting point of the germanium material.The research found that the Raman peak after recrystallization shifted to high wavenumber direction at 3.2 cm^-1 and the FWHM decreases 0.17 cm^-1,greatly improving the quality germanium core fiber.Finally,the simulation of CO₂ laser annealing is carried and the experimental environment was introduced.The temperature field distribution of germanium core fiber of laser heating is analyzed,and the influence of different laser powers and different fiber moving rates on the temperature field distribution at the laser heating point is compared.As the fiber moving rate increases,the corresponding appropriate laser heating power is also increasing.The appropriate laser power and fiber scanning rate for laser heating treatment of germanium core fibers are also required to be further validated.This paper also introduces the experimental environment of laser annealing,which lays a foundation for the experimental study of laser annealing.