Analysis of guided polarization modes in multimode rib waveguide by finite difference method

The multimode devices, which are also polarization-sensitive, have been widely used in modern optical communication system. In some cases, the modal properties, including the modal propagation constants and the modal fields of every order, must be given for the device design. The scalar finite difference beam propagation method (FD-BPM) is extended to solve this polarization-related problem. The different finite difference schemes corresponding to different polarized directions, which satisfy different boundary continual conditions, are formulized and the alternate directions implicit (ADI) FD-BPM were used to deal with the three dimensional (3D) waveguide. The guided modal properties of a 3D rib waveguide including the propagation constants and modal field distributions up to ten ranks were obtained and illustrated as an example.