Research About Fiber Coupling Technology

The fiber coupling technology is a kind of technology that researches how to couple the optical power into a particular fiber, It is the basic of optical fiber communication systems. However through studying the coupling technology exited, we find there is not a kind of technology that can meet this condition:without damaging the communication fiber, the light can be coupled into it from side. So in this paper we want to find this technology.Based on the purpose above, a new coupling model-"polished-bended fiber-fiber side coupling" model is proposed and then a theoretical analysis, a simulation analysis and an experiment about it are given. The details are shown in the following:Firstly, through looking up the technologies of the fiber-fiber side coupling exited, we find that all of these technologies damage both of fibers more or less. So in this paper, a new technology that can inject the light into the fiber from side without damage is expected to get.Secondly, using the beam propagation method (BPM) and coupled-mode theory (CMT), a detail theoretical analysis about fiber-fiber side coupling technology is given. Meanwhile, in order to realize our aim, some possible ways and rules like matching of wave vector and radiation field are put forward. Basing on the methods and rules, a detail introduction about "polished-bended fiber-fiber side coupling" model is given.Thirdly, a brief introduction about BeamPROP is shown. Based on the software, an equivalent model is proposed and then a simulation about this model is carried out. The result shows that when PL=3.7μm、 R=10100μm、nb=1.45, through22760μm coupling, the injected power can reached into30%of the input power. The result also shows different coupling lengths can be chosen to achieve different splitting ratios.Finally, a polishing system is set up and the fiber needed is successfully polished based on this system. Using the fiber polished, an experiment is taken and the result shows that only0.3%of the input power is injected into the fiber. There is a big gap between the result of experiment and the simulation, so several possible reasons about the difference are presented and we hope to improve in the following experiment.