A New Theoretical Model For1×2Single-mode Fiber Fused Biconical Taper Couplers

With the improvement of fiber-optic network, the usage amount of optical fiber coupler, as an optical passive component, ranks second place in optical communication, optical detection and sensing technology. Optimization of the theoretical model contributes to research and development of new fused taper devices.Firstly, this paper briefly introduces the application and progress of the fused biconical tapered coupler. The principles of three types of couplers are introduced and the fabrication methods of optic fiber couplers, including etching, polishing and fused method, are recommended in detail. Fused biconical taper system is introduced and the properties and advantages of fused biconical tapered coupler are demonstrated. FBT coupler is suitable for mass production and application.Secondly, optical waveguide coupled-mode theory is introduced. Under the condition of the weakly guiding approximation, the coupled power between two waveguides was analyzed for different boundary conditions.Thirdly, the shape models of fiber tapers are introduced. The coupling coefficients under the weak and strong fusion conditions are calculated. The errors between the theoretical power coupling curve under the weak and strong fusion conditions and the experimental power coupling curve are analyzed.Fourthly, the sectional view of1x2type fiber-optic coupler is observed. Based on observation, the combination of the weak and strong fusion methods is proposed, which can describe the variation trend of the coupling coefficients of the coupler better. The simulation results using the new theoretical model fit very well with the experimental power coupling curve. Compared with other models, the theoretical wavelength spacing simulated by the new theoretical model is much closer to the experimental wavelength spacing of the coupler, the new theoretical model provides a more effective method to investigate the theory of FBT coupler.Fifthly, combined with new coupling theory, the1490/1550nm WDM is designed and achieved. The influence of the polarization on1490/1550nm WDM is analyzed.