Scalable variable-index elasto-optic metamaterials for macroscopic optical components and devices

• Published in: Nature communications Vol. 8; no. 1; p. 16090
• Main Authors: Shin, Dongheok, Kim, Junhyun, Kim, Changwook, Bae, Kyuyoung, Baek, Seunghwa, Kang, Gumin, Urzhumov, Yaroslav, Smith, David R., Kim, Kyoungsik
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.07.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/399/1015; 639/624/400/1105; Aerogels; Broadband; Devices; Diodes; Genetic transformation; Humanities and Social Sciences; Lenses; Metamaterials; multidisciplinary; Nanofabrication; Optical components; Optics; Refractivity; Science; Science (multidisciplinary); Solid mechanics; Transparency; Visible spectrum; White light
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms16090

Optical metamaterials with an artificial subwavelength structure offer new approaches to implement advanced optical devices. However, some of the biggest challenges associated with the development of metamaterials in the visible spectrum are the high costs and slow production speeds of the nanofabrication processes. Here, we demonstrate a macroscale (>35 mm) transformation-optics wave bender (293 mm 2 ) and Luneburg lens (855 mm 2 ) in the broadband white-light visible wavelength range using the concept of elasto-optic metamaterials that combines optics and solid mechanics. Our metamaterials consist of mesoscopically homogeneous chunks of bulk aerogels with superior, broadband optical transparency across the visible spectrum and an adjustable, stress-tuneable refractive index ranging from 1.43 down to nearly the free space index (∼1.074). The experimental results show that broadband light can be controlled and redirected in a volume of >10 5 λ × 10 5 λ × 10 3 λ , which enables natural light to be processed directly by metamaterial-based optical devices without any additional coupling components. Large-scale graded-index metamaterial devices are difficult to fabricate owing to limitations of typical micro- and nanofabrication approaches. Here, Shin et al . demonstrate millimetre-scale transformation elements based on elasto-optic metamaterials made from aerogels.