Near-zero-index materials for photonics


The discovery, design and development of materials are critically linked to advances in many areas of research, and optics is no exception. Recently, the spectral region in which the index of refraction of a material approaches zero has become a topic of interest owing to fascinating phenomena, such as static light, enhanced nonlinearities, light tunnelling and emission tailoring. As a result, such near-zero-index (NZI) materials bridge materials development and optical research. Here, we review recent advances in various classes of NZI platforms, with particular focus on homogeneous materials, including metals, semi-metals, doped semiconductors, phononic and interband materials, discussing the novel optical phenomena that they can produce. We also overview the developments in a key area for NZI materials, nonlinear optics, and survey some of the future goals in the field, such as the development of tailorable NZI materials in the visible range and the improvement of the theoretical description of the nonlinear enhancements in these materials.

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Fig. 1: Overview of the effects observed in near-zero-index materials.
Fig. 2: Comparison of experimentally realized bulk homogeneous ε-near-zero and near-zero-index materials.
Fig. 3: Studies of near-zero-index and ε-near-zero properties in homogeneous materials.
Fig. 4: Nonlinear optics in near-zero-index media.


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N.K. would like to acknowledge support from the Air Force Office of Scientific Research Young Investigator Program (FA9550-18-1-0151), the Virginia Microelectronics Consortium Seed Grant and the Virginia Commonwealth University Presidential Research Quest Fund. The Purdue team acknowledges support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under award DE-SC0017717 (A.B. and V.M.S.) and the Air Force Office of Scientific Research under award FA9550-18-1-0002 (C.D.).

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N.K. and C.D. compiled and prepared the manuscript. All authors contributed to the editing and revision of the manuscript.

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Correspondence to Nathaniel Kinsey or Vladimir M. Shalaev.

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Kinsey, N., DeVault, C., Boltasseva, A. et al. Near-zero-index materials for photonics. Nat Rev Mater 4, 742–760 (2019).

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