Low-loss and wide-band polarization converter based on a hybrid plasmonic waveguide with symmetric Ag strips

We propose a polarization converter (PC) based on mode coupling in a hybrid plasmonic waveguide (HPW), comprising a Si waveguide, SiO2 layers surrounding the Si core, and two symmetrically arranged metal strips with respect to the optical axes. In this HPW structure, the surface-plasmon-polariton modes at the metal and SiO2 interfaces are hybridized with traditional optical modes within the SiO2 layer Two orthogonal hybrid polarization modes are thus excited. By exploiting the mode characteristics of these two hybrid polarization modes, a compact polarization converter is realized. Simulations indicate that polarization conversion is achieved with a polarization conversion efficiency (PCE) of 99.9%, an insertion loss (IL) of 0.82 dB and an extinction ratio (ER) of 30.4 dB at a wavelength of 155 nm for a conversion length of 4.58μm. For the C-band, in a wavelength range of 1530-1565 nm the PCE is greater than 99.6% the IL is below 1 dB and the ER is larger than 24 dB. These performance values are an improvement over those reported HPW-based PCs