The two important structure parameters(transition length and branch height) are simulated respectively by FD-BPM.The results provide a useful reference for designing and fabricating the Y-branch waveguide.At last,the thesis designs detailed structure of the asymmetric Y-branch triplexer,which includes the theory of the triplexer and the design of the unitary structure.In detail,it includes the design of the asymmetric waveguide,the height and width of the cross section of the waveguide,the length and the angle of the Y-branch waveguide.The effect of the angle and the length of the Y-branch on the insertion loss and crosstalk is analyzed by the combination of effective index method and waveguide simulation software BeamPROPTM.Polarization dependence is a large problem lying in this structure.Based on the birefringence material, polarization dependence problem is effectively solved.Based on these analyses,the whole structure of the triplexer based on the polymer material PPESK is developed.The simulation result shows that this proposed triplexer can be used in FTTH application with low insertion loss,low crosstalk and polarization-independent.
