Improvement On The Theoretical Model Of 1×2 Single-Mode Fiber Fused Biconic Taper Couplers

1 X 2 single-mode FBT fiber coupler is one of the most important optical passive components. The demand of fiber couplers is increasing stupendously with the rapid developing of the all-optical-networks (AON) and the accelerated deployment of FTTH all over the world. Thus study on the theoretical model of the FBT coupler is very important to improve produce process and efficiency.In the first part of this paper, the importance of the fiber coupler on the AON and two typical FBT fiber components is introduced. The class and performance of optical components are described detail. Three types of fabrication methods of fiber passive components are compared, the advantage and disadvantage between FBT and PLC are also compared.In the second part, the coupling characteristics of the taper-structure composite waveguide which make up of two fibers is study detail base on the Coupling-Mode-Theory. The expressions of the coupling coefficient and coupling power are educed.In the third part, the appropriate continuous functions have been chosen to describe geometry characteristic of fused taper and fused coefficient of two fibers, thus a simple and exact theoretical model of 1 X 2 single-mode FBT fiber coupler is established base on the weak-guide approximation and weak-coupling theory.In the last part of this paper, the fabrication process and design parameter of three mainstream FBT fiber components (included WDM, single-windows narrow-band splitter and dual-windows wide-band splitter) are analyzed base on 1 X 2 single-mode FBT fiber coupler theoretical model.