Low-Loss and Wide-Band Polarization Converter Based on a Hybrid Plasmonic Waveguide with Asymmetric Ag Strips

A polarization converter (PC) based on the mode coupling in a hybrid plasmonic waveguide (HPW) is proposed. This PC comprises a Si core, a low index insulator layer surrounding the Si core, and two asymmetrically arranged Ag strips. Two orthogonal hybrid polarization modes are excited within the low index insulator layer. By exploiting the mode characteristics of these two hybrid polarization modes, a compact and low loss polarization converter can be realized. As a comparison, SiO2 and Al2O3 are used as the low index layer. Numerical simulations show that a better polarization conversion performance is obtained when SiO2 is used in the HPW-PC, which exhibits a polarization conversion efficiency (PCE) of 99.99%, an insertion loss (IL) of 0.82dB and an extinction ratio (ER) of 30.4 dB at the wavelength of 1550 nm for a conversion length of 4.58 mu m. Also, for the C-band, the PCE is greater than 99.6%, the IL is below 1dB and the ER is larger than 24dB.