Abstract
A compact and broadband silicon-based transverse-electric (TE)-pass polarizer based on a symmetrical triple-guide directional coupler (TW-DC) is presented and analyzed in detail, assisted with subwavelength gratings (SWGs) and hybrid plasmonic waveguides (HPWs), where the SWGs are involved at the inner part of its central waveguide and two HPWs are introduced and symmetrically located at its outer sides. By carefully improving the structural parameters, only the injected TE mode can be supported by SWGs, and it passes through the device directly due to phase mismatching, while the input TM mode will be supported in the strip waveguides and coupled to the adjacent HPWs due to phase matching and gradually attenuated via the metals. As a result, a compact TE-pass polarizer is realized. Results show that the proposed polarizer has a total coupling length of 6 µm, with an extinction ratio (ER) of 31.2 dB, insertion loss (IL) of 0.1 dB, and reflection loss (RL) of ${-}{26.2}\;{\rm dB}$ at 1.55 µm, and its operation bandwidth can be up to 270 nm (from 1.43 to 1.7 µm) for ${\rm ER} \gt {20}\;{\rm dB}$ and ${\rm IL} \lt {1}\;{\rm dB}$. In addition, fabrication tolerances to the key structural parameters and field evolution through the proposed device are given.
© 2021 Optical Society of America
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