Research On The Key Technologies Of Communication Optical Cable Loss Analysis In High Altitude Area

With the sustainable development of modern communication technology and the growing users demand,the building of communication infrastructure is gradually increasing.Whereas,the construction and maintenance of communication infrastructure in high altitude areas has always been a difficult issue in engineering,for the reason that the harsh natural environment,steep terrain,inaccessible people,difficult traffic of high altitude areas and so on.Ultra low loss fiber(ULL)has many advantages in ultra low transmission loss,stable performance and long haul transmission,hence,it has been gradually applied to the construction of backbone network in high altitude areas and some special scenes in plain areas in recent years.Although the application of ULL fiber has improved the quality of signal transmission,there are still some problems in splice loss to be solved.Single mode optical fiber(SMF)is generally used in the existing backbone network for signal transmission.How to reduce the splice loss of fusion the same type of fiber and different types of fibers in the harsh environment is an urgent problem to be solved.This work is supported by the national key project of networking project in central Tibet "Key performance and technology research of facilities in power communication under micrometeorology in plateau areas".This thesis mainly focuses on the splice loss of optical fiber in high altitude area.Specially,including the modeling of splice loss for ULL single-mode optical fiber affected by altitude,the influence of fusion current on core expansion and dopants diffusion of SMF and ULL fiber fusion at different altitudes,and the modeling of SMF and ULL fiber splice loss affected by altitude.Additionally,the corresponding simulations and experiments are carried out.The main work and innovation achievements of this thesis are listed as follows:1.Aiming at the splice loss of ULL single mode optical fiber in high altitude areas,a mathematical model of splice loss of ULL single mode optical fiber affected by altitude is proposed.The model modifies the existing classical Marcuse model,it takes the splice loss caused by the mismatch in mode field diameters(MFD),angular misalignment and lateral misalignment into account,as well as the influence of atmospheric pressure on splicing angular misalignment owing to high altitude.The force of the fiber butt-joint increases as the altitude increases,and the angular misalignment of fiber fusion will be larger,furthermore the splice loss will be increased.Subsequently,the relationship between the splice loss of ULL single-mode fiber and altitude is revealed.The fusion experiments of ULL single-mode fiber from plain to high altitude are carried out,and the experimental results are in good agreement with the established model.By comparing with Marcuse model and Das model,the accuracy and superiority of the proposed model in high altitude areas are both verified,and the model can be used as a reference for the future research of splice loss in Plateau areas.2.Aiming at the core expansion and dopants diffusion in SMF and ULL fiber fusion,the influences of fusion current on the core expansion,dopants diffusion and the fusion time in the course of splicing SMF and ULL fiber are mainly considered.The variations of core radius and the mode field diameter in the fusion process are analyzed,furthermore,the influence of fusion current on the splice loss of SMF and ULL fiber is researched,and the fiber fusion and simulations at different altitudes are carried out.The simulations are in good agreement with the fusion results.If the result of our research is applied to the current calibration of modern optical fiber fusion splicer,the splice loss of SMF and ULL fiber will be deduced further.3.In the high altitude area,there are more factors that affect SMF and ULL fiber fusion,and the fusion operation will be more difficult.Thereby,in the context of the increasing joints between SMF and ULL fiber,a model of splice loss of SMF and ULL fiber in high altitude area is proposed.The model considered the variation in fusion current of fusion splicer caused by the lower atmospheric pressure in high altitude area,as well as the dopants diffusion in the fiber core,which contributes to the variation of mode field diameter.The effect of atmospheric pressure on angular misalignment of fiber fusion is also taken into account.Subsequently,the splice loss of SMF and ULL fiber in high altitude area can be modeled as:the loss of thermal expansion region of core,the lateral misalignment and angular misalignment.The fusion experiments of SMF and ULL fiber are carried out at different altitude from plain to high altitude.The experimental results are in accordance with the splice loss model proposed in this research,and the accuracy of the proposed model is verified.By comparison with Ratuszek model,the model proposed in this paper is more consistent with the experimental data than Ratuszek model in high altitude area,which further verifies the superiority of the model proposed in this paper and its applicability in high altitude areas.