Microstructure And Performance Of Flourine Doped Large Core Energy Optical Fibers

The large core energy fibers is a special fibers different from the conventional communication fibers,and can be widely used in the fields of laser medical,military,industrial processing,solar energy utilization,etc.,and has a broad application prospects.At present,although China is already a major fibers exporting country,its key core technologies have been blocked by foreign countries in the sensitive fields such as military and laser nuclear physics.The large-core energy fibers products used in China are all dependent on imported from abroad.In order to independently develop highperformance of large-core energy fibers,the dissertation compares the effect of cladding with fluorine doping on self-made optical fibers preforms and large core energy fibers,and compares self-made large core energy fibers with foreign products and self-made large core energy.The stability of the fibers has been deeply analyzed.Effects of fluorine-doped cladding on the composition and structural properties of optical fibers preforms and large core energy fibers were investigated.The research on the structure,composition and transmission properties of large-core energy fibers by fluorine-doped optical fibers preform prepared by two-step method(OVD+MCVD).The Studies on composition and transmission properties show that the production process is for different optical fibers preforms.The corresponding drawing process has an important impact on the morphology and performance of the fibers structure.By adjusting the reaction material ratio,evaporation pressure,moving speed of the target rod and correction coefficient,the optical fibers preform with good fluorine-doped cladding and core interface is obtained.The fluorine content of the drawn cladding is 1.25% wt% compared with the fluorine content of 0.52% wt%.The fibers can significantly reduce the water peaks of the water molecules and fibers generated during the preparation of the optical fibers preform,and reduce the strain bond of the fibers glass network to improve the transmission loss performance of the fibers.An in-depth comparative analysis of the self-made large-core energy fibers and two foreign products of the same type were carried out.The measurement of the surface composition of the fibers cladding layer shows that the other components are relatively close except that the fluorine doping amount of the self-made fibers cladding layer is relatively small.Moreover,the SEM photograph shows that the surface of the self-made fibers cladding is smooth and uniform,and the cladding and core steps are not present in the cross section.The transmission loss spectrum of the optical fibers show that the transmission loss of the self-made fibers is 2 dB/km in the first window of 850 nm and has reached the better level compared with the same type of abroad products.The relationship between the fluorine doping content of the fibers cladding and the transmission loss coefficient is obtained.The optimal content of fluorine doping in the fibers cladding is about 1.85 wt% or near it.A detailed analysis of the stability of the self-made large core energy fibers was made.The fibers-optic at high-low temperature experiment in the range of-100~100 °C shows that the transmission loss coefficient of the large-core energy fibers in the first window fluctuates with the temperature in the range of 2.543~ 4.237 dB/km,and it is in the range of-75 °C~60 °C.The transmission loss coefficient is relatively stable in that range,and there is a relatively large fluctuation above this range.In addition,after the heat and cold test,the transmission loss coefficient measured at room temperature has a large fluctuation in the first 5 days,and the value measured after 5 days tends to be stable.In addition,for the structural parameters of self-made optical fibers,electron irradiation simulation experiments show that when the incident electron energy is less than 85 KeV,the electron energy is completely distributed in the fibers coating layer.When the incident electron energy is equal to 93 KeV the incident electrons just reach the core.When 95% of the incident electron energy is deposited at the core and cladding,the energy of the incident electron is 260 KeV.Electrons can penetrate the energy fibers when the incident electron energy reaches 1 MeV.