Ultracompact TM-Pass Silicon Nanophotonic Waveguide Polarizer and Design

• Main Authors: Qian Wang, Seng-Tiong Ho
• Format: Article
• Language: English
• Published: IEEE 2010-01-01
• Series: IEEE Photonics Journal
• Subjects: Silicon nanophotonics; waveguides
• Online Access: https://ieeexplore.ieee.org/document/5401087/

An ultracompact transverse magnetic (TM)-pass polarizer based on silicon nanophotonic waveguides is proposed, which contains two tapered waveguides sandwiching a narrow waveguide section only supporting TM-mode propagation. A full-vectorial eigenmode solver is employed to determine the appropriate cross section of the silicon nanophotonic waveguide. The device is first designed in a 2-D approximate model using a wide-angle beam propagation method, and numerical verification is carried out afterward using a parallel full-vectorial 3-D finite-difference time-domain simulation. Both approaches indicate that the finite thickness of the buried SiO₂ layerand the reflection at the substrate play important roles on the extinction ratio of the device. A designed numerical example shows an extinction ratio of ~26 dB for the waveguide polarizer with a length of ~10 ¿m, while the insertion loss for the TM mode is negligible.