Rigorous analysis of polarization-preserving fiber-optic directional couplers

A new approach to analyze directional couplers of arbitrary cross section is presented. The ultimate objective is to obtain accurate coupling coefficients for various coupler parameters and to establish the optimal conditions for practical applications of polarization-preserving fiber-optic couplers (PFDCs). The even and odd super-modes for each polarization are obtained using a recently developed Yee´s mesh finite-difference vectorial-beam-propagation method (YMFD-VBPM). Subsequently, the coupling coefficient for each polarization is then obtained