Highly tunable refractive index visible-light metasurface from block copolymer self-assembly.
The refractive index of natural transparent materials is limited to 2-3 throughout the visible wavelength range. Wider controllability of the refractive index is desired for novel optical applications such as nanoimaging and integrated photonics. We report that metamaterials consisting of period and symmetry-tunable self-assembled nanopatterns can provide a controllable refractive index medium for a broad wavelength range, including the visible region. Our approach exploits the independent control of permeability and permittivity with nanoscale objects smaller than the skin depth. The precise manipulation of the interobject distance in block copolymer nanopatterns via pattern shrinkage increased the effective refractive index up to 5.10. The effective refractive index remains above 3.0 over more than 1,000 nm wavelength bandwidth. Spatially graded and anisotropic refractive indices are also obtained with the design of transitional and rotational symmetry modification.
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Ju Young
JY
Kim
Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea.
Hyowook
http://orcid.org/0000-0002-6000-7234
H
Kim
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Bong Hoon
BH
Kim
Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea.
Taeyong
T
Chang
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Joonwon
J
Lim
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Hyeong Min
HM
Jin
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Jeong Ho
JH
Mun
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Young Joo
YJ
Choi
Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea.
Kyungjae
K
Chung
Department of Materials Science and Engineering, KAIST, Daejeon 34141, Republic of Korea.
Jonghwa
http://orcid.org/0000-0003-0712-464X
J
Shin
Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
Shanhui
S
Fan
Department of Materials Science and Engineering, National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, KAIST, Daejeon 34141, Republic of Korea.
Sang Ouk
SO
Kim
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