Design methodology for metal-clad polarizer in SOI waveguides

摘要

In this paper we give a specific design methodology for the design of a metal-clad SOI waveguide TE-pass polarizer based on phase matching between the guided TM mode of the dielectric waveguide and surface plasmon TM mode supported by a metal-dielectric interface. The design criterion explicitly shows the necessity of a high index Si_3N_4 layer between the silica cladding and metal. The methodology is used to design a SOI waveguide polarizer in ridge configuration. The finite element method is used to characterize the ridge waveguides and propagations. The proposed polarizer has a very short device length of 5.5 μm with extinction ratio better than 30 dB and negligible loss for the TE polarization.