Semiconductor-based circularly polarized emission by using topological edge states derived from optical Weyl points

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K18857
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 21:Electrical and electronic engineering and related fields
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: Takahashi Shun 京都工芸繊維大学, 電気電子工学系, 准教授 (60731768)
• Project Period (FY): 2018-06-29 – 2022-03-31
• Keywords: トポロジカルフォトニクス

Outline of Final Research Achievements

Three-dimensional chiral photonic crystals can form optical Weyl points which show topologically unique properties. We numerically confirmed the existence of such optical Wely points in a chiral photonic crystal, and revealed that the topological edge states derived from the Weyl point were circularly polarized. Based on this numerical result, we performed transmission measurements in a microwave region, and successfully measured unique transmission phenomena at a Weyl point and topological edge states. The obtained edge states were actually polarized in circular polarization. Furthermore, we fabricated semiconductor-based chiral photonic crystals, and performed angle-resolved transmission measurements in an optical region. The obtained results indicate topological edge states derived from a Weyl point.

Free Research Field

電子デバイス・電子機器

Academic Significance and Societal Importance of the Research Achievements

本研究では、半導体の高い屈折率を活かして作製したカイラルナノ構造であるため、外乱の影響を受けにくい、10ミクロン程度の小型な円偏光発光素子が可能となるほか、既存の半導体素子との整合性も高く集積化に向く。また、光ワイル点に起因する容易なエッジ状態形成により、導波光の動的制御も期待できる。さらに、左回り円偏光と右回り円偏光が、上向き電子スピンと下向き電子スピンにそれぞれ一対一で対応することを利用すれば、実用に不向きな外部磁場の代わりに、ワイル点を有するカイラル構造に起因したトポロジカルエッジ状態によってスピンを制御できるため、スピントロニクスへの応用も期待できる。