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Chen G, Zhou J, Chen L, Tian F, Liu Z. Infrared color-sorting metasurfaces. NANOSCALE 2024; 16:14490-14497. [PMID: 39022992 DOI: 10.1039/d4nr01891e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
The process of sorting light based on colors (photon energy) is a prerequisite in broadband optical systems, typically achieved in the form of guiding incoming signals through a sequence of spectral filters. The assembly of filters often leads to lengthy optical trains and consequently, large system footprints. In this work, we address this issue by proposing a flat color-sorting device comprising a diffraction grating and a dielectric Huygens' metasurface. Upon the incidence of a broadband beam, the grating disperses wavelengths to a continuous range of angles in accordance with the law of diffraction. The following metasurface with multiple paired Huygens' resonances corrects the dispersion and binds wavelengths to the corresponding waveband with a designated output angle. We demonstrate the sorting efficacy by designing a device with a color-sorting metasurface with two discrete dispersion-compensated outputs (10.8 ± 0.3 μm and 11.9 ± 0.3 μm), based on the proposed approach. The optimized metasurface possesses an overall transmittance exceeding 57% and reduces lateral dispersion by 90% at the output. The proposed color-sorting mechanism provides a solution that benefits the designing of metasurfaces for miniature multi-band systems.
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Affiliation(s)
- Guanghao Chen
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
| | - Junxiao Zhou
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
| | - Li Chen
- Department of Materials Science and Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Fanglin Tian
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
| | - Zhaowei Liu
- Department of Electrical and Computer Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.
- Department of Materials Science and Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
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Nielsen KES, Carlsen MA, Zambrana-Puyalto X, Raza S. Non-imaging metasurface design for collimated beam shaping. OPTICS EXPRESS 2023; 31:37861-37870. [PMID: 38017906 DOI: 10.1364/oe.504595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/14/2023] [Indexed: 11/30/2023]
Abstract
Non-imaging optical lenses can shape the light intensity from incoherent sources to a desired target intensity profile, which is important for applications in lighting, solar light concentration, and optical beam shaping. Their surface curvatures are designed to ensure optimal transfer of energy from the light source to the target. The performance of such lenses is directly linked to their asymmetric freeform surface curvature, which is challenging to manufacture. Metasurfaces can mimic any surface curvature without additional fabrication difficulty by imparting a spatially-dependent phase delay using optical antennas. As a result, metasurfaces are uniquely suited to realize non-imaging optics, but non-imaging design principles have not yet been established for metasurfaces. Here, we take an important step in connecting non-imaging optics and metasurface optics, by presenting a phase-design method for beam shaping based on the concept of optimal transport. We establish a theoretical framework that enables a collimated beam to be redistributed by a metasurface to a desired output intensity profile. The optimal transport formulation leads to metasurface phase profiles that transmit all energy from the incident beam to the output beam, resulting in an efficient beam shaping process. Through a variety of examples, we show that our approach accommodates a diverse range of different input and output intensity profiles. Last but not least, a full field simulation of a metasurface has been done to verify our phase-design framework.
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Fiedler S, Stamatopoulou PE, Assadillayev A, Wolff C, Sugimoto H, Fujii M, Mortensen NA, Raza S, Tserkezis C. Disentangling Cathodoluminescence Spectra in Nanophotonics: Particle Eigenmodes vs Transition Radiation. NANO LETTERS 2022; 22:2320-2327. [PMID: 35286099 DOI: 10.1021/acs.nanolett.1c04754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cathodoluminescence spectroscopy performed in an electron microscope has proven a versatile tool for analyzing the near- and far-field optical response of plasmonic and dielectric nanostructures. Nevertheless, the transition radiation produced by electron impact is often disregarded in the interpretation of the spectra recorded from resonant nanoparticles. Here we show, experimentally and theoretically, that transition radiation can by itself generate distinct resonances that, depending on the time-of-flight of the electron beam inside the particle, can result from constructive or destructive interference in time. Superimposed on the eigenmodes of the investigated structures, these resonances can distort the recorded spectrum and lead to potentially erroneous assignment of modal characters to the spectral features. We develop an intuitive analogy that helps distinguish between the two contributions. As an example, we focus on the case of silicon nanospheres and show that our analysis facilitates the unambiguous interpretation of experimental measurements on Mie-resonant nanoparticles.
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Affiliation(s)
- Saskia Fiedler
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - P Elli Stamatopoulou
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Artyom Assadillayev
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
- Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kongens Lyngby, Denmark
| | - Christian Wolff
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Hiroshi Sugimoto
- Department of Electrical and Electronic Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
| | - Minoru Fujii
- Department of Electrical and Electronic Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
| | - N Asger Mortensen
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
- Danish Institute for Advanced Study, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Søren Raza
- Department of Physics, Technical University of Denmark, Fysikvej, DK-2800 Kongens Lyngby, Denmark
| | - Christos Tserkezis
- Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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Ossiander M, Huang YW, Chen WT, Wang Z, Yin X, Ibrahim YA, Schultze M, Capasso F. Slow light nanocoatings for ultrashort pulse compression. Nat Commun 2021; 12:6518. [PMID: 34764297 PMCID: PMC8586156 DOI: 10.1038/s41467-021-26920-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 10/22/2021] [Indexed: 11/09/2022] Open
Abstract
Transparent materials do not absorb light but have profound influence on the phase evolution of transmitted radiation. One consequence is chromatic dispersion, i.e., light of different frequencies travels at different velocities, causing ultrashort laser pulses to elongate in time while propagating. Here we experimentally demonstrate ultrathin nanostructured coatings that resolve this challenge: we tailor the dispersion of silicon nanopillar arrays such that they temporally reshape pulses upon transmission using slow light effects and act as ultrashort laser pulse compressors. The coatings induce anomalous group delay dispersion in the visible to near-infrared spectral region around 800 nm wavelength over an 80 nm bandwidth. We characterize the arrays' performance in the spectral domain via white light interferometry and directly demonstrate the temporal compression of femtosecond laser pulses. Applying these coatings to conventional optics renders them ultrashort pulse compatible and suitable for a wide range of applications.
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Affiliation(s)
- M Ossiander
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA.
| | - Y-W Huang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA
- Department of Photonics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan
| | - W T Chen
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA
| | - Z Wang
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010, Graz, Austria
| | - X Yin
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA
| | - Y A Ibrahim
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA
- University of Waterloo, Waterloo, ON, N2L 3G1, Canada
| | - M Schultze
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010, Graz, Austria
| | - F Capasso
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA.
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Yaqoob MZ, Ghaffar A, Alkanhal MAS, Naz MY, Alqahtani AH, Khan Y. Electromagnetic surface waves supported by a resistive metasurface-covered metamaterial structure. Sci Rep 2020; 10:15548. [PMID: 32968140 PMCID: PMC7511986 DOI: 10.1038/s41598-020-72396-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 08/17/2020] [Indexed: 11/16/2022] Open
Abstract
This study examines the analytical and numerical solution of electromagnetic surface waves supported by a resistive metasurface-covered grounded metamaterial structure. To simulate the metamaterial, the Kramers-Kronig relation based on the causality principle is used, while the modeling of the resistive metasurface has been done by implementing the impedance boundary conditions. The analytical expressions for the field phasors of surface waves are developed for the transverse magnetic (TM) polarized mode and transverse electric (TE) polarized mode. The characteristic equations are computed for both modes, and the unknown propagation constant is evaluated numerically in the kernel. After computation, the dispersion curves, electric field profiles, effective mode index ([Formula: see text]), and phase speeds ([Formula: see text]) are presented for both the TM and TE polarized modes. To study the tunability of surface waves, the influence of the thickness of the metamaterial slab ([Formula: see text]), effective permittivity of the metamaterial ([Formula: see text]), thickness of the resistive metasurface ([Formula: see text]), and effective permittivity of the metasurface ([Formula: see text]) on all the numerical results has been studied. However, the geometrical parameters are found to be more sensitive to the effective mode index ([Formula: see text]) and phase speed ([Formula: see text]) of the surface waves. The results are consistent with the published results, which reflects the accuracy of the work. It is concluded that the appropriate choice of parameters can be used to achieve surface waves with the desired characteristics in the GHz range. The present work may have potential applications in surface waveguide design, surface wave speed controllers, surface communication devices, and light trapping configurations.
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Affiliation(s)
- M Z Yaqoob
- Department of Physics, University of Agriculture, Faisalabad, Pakistan
- Department of Physics, Government College University, Faisalabad, Pakistan
| | - A Ghaffar
- Department of Physics, University of Agriculture, Faisalabad, Pakistan.
| | - Majeed A S Alkanhal
- Department of Electrical Engineering, King Saud University, Riyadh, Saudi Arabia.
| | - M Y Naz
- Department of Physics, University of Agriculture, Faisalabad, Pakistan
| | - Ali H Alqahtani
- Department of Electrical Engineering, College of Applied Engineering, Al-Muzahimiyah Branch, King Saud University, Al-Muzahmiya, Saudi Arabia
| | - Y Khan
- Department of Electrical Engineering, King Saud University, Riyadh, Saudi Arabia
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