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Metasurfaces that can refract and focus light in unique ways provide the opportunity for advanced light manipulation and development of novel applications. Due to the flat nature of metasurfaces (typical thickness < 100nm), conventional three-dimensional optical elements such as prisms or lenses could be replaced by flat, low-profile, and low-cost versions. In addition, the optical response of near-zero refractive index metasurface systems, i.e., vanishing permittivity and permeability values, have been shown to exhibit unique optical properties. Those features can be exploited in various optical applications such as wavefront engineering, radiation pattern tailoring, non-reciprocal magneto-optical effects, nonlinear ultrafast optical switching, and broadband perfect absorption. However, most of the studies on epsilon-near-zero (ENZ) optical properties are limited to the excitation of ENZ mode in the planar structures or meta-surfaces with short interaction length, restricting the excitation platform for novel optical device applications.
In this talk, I will report a novel optical waveguide design of a hollow step index fiber modified with a thin layer of conducting oxide epsilon-near-zero materials. We show an excitation of highly confined waveguide mode in the proposed fiber near the wavelength where permittivity of conducting oxide material approaches zero [1]. I will present our study on “meta”-optical fiber by integrating metasurfaces with optical fibers to develop novel and ultracompact in-fiber optical devices such as an optical fiber metalens and color filter [2,3]. These advanced “meta”/ENZ-optical fibers open the path to revolutionary in-fiber optical imaging and communication devices.
1. K. Minn, A. Anopchenko, J. Yang, H. W. Lee, “Excitation of epsilon-near-zero resonance in ultra-thin indium tin oxide shell embedded nanostructured optical fiber,” Nature Scientific Reports 8, 2342 (2018).
2. J. Yang, I Ghirmire, P. C. Wu, S. Gurung, C. Arndt, D. P. Tsai, H. W. Lee, “Photonic crystal fiber metalens”, submitted (2018).
3. Indra Ghimire, Jingyi Yang, Sudip Gurung, Satyendra K. Mishra and Ho Wai Howard Lee,” Polarization dependent photonic crystal fiber color filter using asymmetric metasurfaces,” Submitted (2018)
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