Design of artificial nanocrystals based on nanocolumns and creation of new optical functionalities

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K14483
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 28020:Nanostructural physics-related
• Research Institution: Yamagata University
• Principal Investigator: OTO TAKAO 山形大学, 大学院理工学研究科, 准教授 (20749931)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Keywords: InGaN / ナノ構造 / メタマテリアル / キラル / 円偏光 / 表面プラズモン

Outline of Final Research Achievements

In this study, we have realized optical functionality that InGaN does not have by designing a unit lattice structure, and we have introduced a chiral structure in which mirror symmetry is eliminated. The chiral structure has different refractive indices for left- and right-circularly polarized light. Therefore, the chiral structure is expected to realize an ultra-compact circularly polarized light source.
Nanopillar structures were fabricated on blue LED substrates by hydrogen environment anisotropic thermal etching. The nanosturcutural effect produced higher emission intensity than a planar structure, and polarization rotation was observed only in the chiral pattern, which was in good agreement with the calculated results of rigorous coupling wave analysis. Because the wavelength at which polarization rotation occurs can be controlled by the period and diameter, it was found that large polarization rotation can be obtained in the visible light region by optimizing the nanostructure.

Free Research Field

半導体光デバイス，光物性工学

Academic Significance and Societal Importance of the Research Achievements

本研究で提案したキラルナノ構造はナノピラー構造を複数配置するだけであるので，従来のナノ構造作製技術をそのまま使用できるが，ナノ構造の設計により従来窒化物半導体が持たない光機能性を実証できたことは可視光デバイスとしての応用範囲の拡大に繋がり，学術的にも社会的にも大きな意義を持つ結果である．今後，光とナノ構造の相互作用という学理を明らかにし，高効率な可視単一円偏光素子が実現できれば，生体内イメージング，3Dディスプレイ光源，可視光通信など，医療・映像・通信分野への様々な応用分野の開拓に発展できると期待される．