L字型Si細線導波路を用いた偏波変換器

摘要

A polarization converter using an L-figured Si wire waveguide is developed and analyzed by the beam-propagation method based on Yee's mesh and the finite-difference time-domain method. We evaluate the polarization conversion length and the insertion loss to optimize the configuration parameters. To achieve wideband operation, the wavelength response of the effective index difference is investigated. When the converter length is chosen to be around 3.2 μm, the converter provides the wideband operation. The extinction ratio is more than 20 dB over a wide wavelength range of 1.3 μm to 1.6 μm, with the insertion loss being a value of less than 0.6 dB. Finally, we propose a polarization converter with two square defects. The insertion loss is reduced to be a value ofrnless than 0.25 dB.%L字型Si細線導波路を用いた偏波変換器を提案し，諸特性をYee格子に基づくビーム伝搬法と有限差分時間領域法を用いて解析する．はじめに，偏波変換長と挿入損失を評価し，構造値の最適化を行う．次に，偏波変換部における2つの直交モード間の実効屈折率差から，広帯域動作に必要な偏波変換部長を検討する．偏波変換部長を3.2μmに選ぶと，波長1.3～1.6μmの広帯域にわたって消光比20dB以上の偏波変換特性を維持できることを示す．また，その帯域内において，挿入損失が0.6dB以下であることを明示する．最後に，導波路に欠落部を2か所設けた偏波変換器を解析し，挿入損失を0.25dB以下に低減できることを明らかにする．