High polarisation extinction ratio of the TM-pass polariser with silicon carbide / graphene / silicon multilayers

Abstract

We propose a compact TM-pass polariser, consisting of silicon (Si) / silicon carbide (SiC) / Si layers. Two graphene sheets are sandwiched between the Si and SiC layers as the interlayer to enhance the interaction with light. The loss characteristics have been investigated by using the finite-difference time-domain (FDTD) method. The proposed structure exhibits a low insertion loss (IL) of $\sim$0.25 $\hbox {dB}$ and a high polarisation extinction ratio (PER) of $\sim$57 $\hbox {dB}$. To verify the robustness of the proposed polariser, we analyse the fabrication tolerance of the waveguide width and the height of the Si and SiC layers. The polariser shows great fabrication error tolerance. In addition, by employing a $100\,\mu \hbox {m}$ long waveguide, a PER of 48.3–59.4 dB is obtained in the visible regime ranging from 400 to 600 nm.