Ordered 3D Thin‐Shell Nanolattice Materials with Near‐Unity Refractive Indices |
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Authors: | Xu A Zhang Abhijeet Bagal Erinn C Dandley Junjie Zhao Christopher J Oldham Bae‐Ian Wu Gregory N Parsons Chih‐Hao Chang |
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Affiliation: | 1. Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, USA;2. Department of Chemical and Bimolecular Engineering, North Carolina State University, Raleigh, NC, USA;3. Air Force Research Laboratory, Dayton, OH, USA |
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Abstract: | The refractive indices of naturally occurring materials are limited, and there exists an index gap between indices of air and available solid materials. With many photonics and electronics applications, there has been considerable effort in creating artificial materials with optical and dielectric properties similar to air while simultaneously being mechanically stable to bear load. Here, a class of ordered nanolattice materials consisting of periodic thin‐shell structures with near‐unity refractive index and high stiffness is demonstrated. Using a combination of 3D nanolithography and atomic layer deposition, these ordered nanostructured materials have reduced optical scattering and improved mechanical stability compared to existing randomly porous materials. Using ZnO and Al2O3 as the building materials, refractive indices from 1.3 down to 1.025 are achieved. The experimental data can be accurately described by Maxwell Garnett effective media theory, which can provide a guide for index design. The demonstrated low‐index, low‐scattering, and high‐stiffness materials can serve as high‐quality optical films in multilayer photonic structures, waveguides, resonators, and ultra‐low‐k dielectrics. |
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Keywords: | 3D periodic nanostructures atomic layer deposition low‐index materials nanolithography porous materials |
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