Production of optical metamaterials with mechanically self-organized nanocoil networks

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K20954
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 18:Mechanics of materials, production engineering, design engineering, and related fields
• Research Institution: Akita University
• Principal Investigator: Muraoka Mikio 秋田大学, 理工学研究科, 教授 (50190872)
• Project Period (FY): 2020-07-30 – 2024-03-31
• Keywords: ナノ材料 / 金属ナノコイル / メタマテリアル / 光学的性質 / テンプレート / 真性応力解放 / 自己還元型溶液 / 自己組織化

Outline of Final Research Achievements

Extending our previous method of self-organization for metallic nanocoils, we succeed in formation of silver nanocoil networks having a coil diameter of 170 nm, less than wave lengths of visible light. The success attributes mainly to use of self-reduction solution for electro-spun nanofibers as a template of Ag nanocoils. The self-reduction solution enhanced thermal decomposition of the template. Ag nanocoil networks were applied to anti-reflection film on metallic surface. The networks in a multi reflection layer between metallic tin film and a metallic surface, showed absorption enhancement of visible light due to a coil effect, Faraday’s electromagnetic induction. The finding implies Ag nanocoil network work as an optical metamaterial with an imaginary part of permeability.

Free Research Field

材料力学，ナノテクノロジー

Academic Significance and Societal Importance of the Research Achievements

自然界には可視光の磁場に応答する物質は存在しない。つまり可視光に対して物質の比透磁率は１に限られる。銀ナノコイル網は，多重反射層内等の磁場が支配的な空間において，透磁率の虚部（磁場エネルギの吸収）を発現する光メタマテリアルとして機能することを発見した本研究の成果は，光メタマテリアル研究分野の進展に大きく貢献する。また，可視光に対する完全反射防止膜への展開もあり光学素子への応用が期待できる。