1
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Chang KH, Lin ZH, Lee PT, Huang JS. Enhancing on/off ratio of a dielectric-loaded plasmonic logic gate with an amplitude modulator. Sci Rep 2023; 13:5020. [PMID: 36977738 PMCID: PMC10050437 DOI: 10.1038/s41598-023-30823-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 03/02/2023] [Indexed: 03/30/2023] Open
Abstract
AbstractPlasmonic waveguides allow focusing, guiding, and manipulating light at the nanoscale and promise the miniaturization of functional optical nanocircuits. Dielectric-loaded plasmonic (DLP) waveguides and logic gates have drawn attention because of their relatively low loss, easy fabrication, and good compatibility with gain and active tunable materials. However, the rather low on/off ratio of DLP logic gates remains the main challenge. Here, we introduce an amplitude modulator and theoretically demonstrate an enhanced on/off ratio of a DLP logic gate for XNOR operation. Multimode interference (MMI) in DLP waveguide is precisely calculated for the design of the logic gate. Multiplexing and power splitting at arbitrary multimode numbers have been theoretically analyzed with respect to the size of the amplitude modulator. An enhanced on/off ratio of 11.26 dB has been achieved. The proposed amplitude modulator can also be used to optimize the performance of other logic gates or MMI-based plasmonic functional devices.
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2
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Goudarzi K, Lee M. Towards Perfect Ultra-Broadband Absorbers, Ultra-Narrow Waveguides, and Ultra-Small Cavities at Optical Frequencies. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2132. [PMID: 35807967 PMCID: PMC9268687 DOI: 10.3390/nano12132132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/14/2022] [Accepted: 06/20/2022] [Indexed: 01/27/2023]
Abstract
In this study, we design ultra-broadband optical absorbers, ultra-narrow optical waveguides, and ultra-small optical cavities comprising two-dimensional metallic photonic crystals that tolerate fabrication imperfections such as position and radius disorderings. The absorbers containing gold rods show an absorption amplitude of more than 90% under 54% position disordering at 200<λ<530 nm. The absorbers containing silver rods show an absorptance of more than 90% under 54% position disordering at 200<λ<400 nm. B-type straight waveguides that contain four rows of silver rods exposed to air reveal normalized transmittances of 75% and 76% under 32% position and 60% radius disorderings, respectively. B-type L-shaped waveguides containing four rows of silver rods show 76% and 90% normalized transmittances under 32% position and 40% radius disorderings, respectively. B-type cavities containing two rings of silver rods reveal 70% and 80% normalized quality factors under 32% position and 60% radius disorderings, respectively.
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Affiliation(s)
- Kiyanoush Goudarzi
- Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Moonjoo Lee
- Department of Electrical Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
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3
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Zhuo X, Li S, Li N, Cheng X, Lai Y, Wang J. Mode-dependent energy exchange between near- and far-field through silicon-supported single silver nanorods. NANOSCALE 2022; 14:8362-8373. [PMID: 35635072 DOI: 10.1039/d2nr01402e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Optical antenna effects endow plasmonic nanoparticles with the capability to enhance and control various types of light-matter interaction. Most reported plasmonic systems can be regarded as single-channel nanoantennas, which rely only on a bright dipole plasmon mode for energy exchange between near- and far-field. Herein we demonstrate a dual-channel plasmonic system that can separate the excitation and emission processes into two energy exchange pathways mediated by the different plasmon modes, offering a higher degree of freedom for the manipulation of light-matter interaction. Our system, consisting of high-aspect-ratio Ag nanorods and Si substrates, can support a series of bright and dark plasmon modes with distinct near- and far-field properties and generate relatively intensive local field enhancement in the gap region. As a proof-of-principle, we take plasmon-enhanced fluorescence of dye molecules as an example to reveal the energy exchange mechanism in the dual-channel plasmonic system. Such a system is potentially also useful for manipulating other types of light-matter interaction. Our work represents a step toward the utilization of a broader class of plasmon resonance for the development of optical antennas and various on-chip nanophotonic components.
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Affiliation(s)
- Xiaolu Zhuo
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
- CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), 20014 Donostia-San Sebastián, Spain
| | - Shasha Li
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
| | - Nannan Li
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
| | - Xizhe Cheng
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
| | - Yunhe Lai
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
| | - Jianfang Wang
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
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4
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Kim G, Lee M. Suppressed Transmission of Long-Range Surface Plasmon Polariton by TE-Induced Edge Plasmon. MICROMACHINES 2021; 12:mi12101198. [PMID: 34683249 PMCID: PMC8538496 DOI: 10.3390/mi12101198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/26/2021] [Accepted: 09/27/2021] [Indexed: 11/30/2022]
Abstract
Work on controlling the propagation of surface plasmon polaritons (SPPs) through the use of external stimuli has attracted much attention due to the potential use of SPPs in nanoplasmonic integrated circuits. We report that the excitation of edge plasmon by TE-polarized light passing across gapped-SPP waveguides (G-SPPWs) leads to the suppressed transmission of long-range SPPs (LRSPPs) propagating along G-SPPWs. The induced current density by highly confined edge plasmon is numerically investigated to characterize the extended radiation length of decoupled LRSPPs by the TE-induced edge plasmon. The suppressed transmission of LRSPPs is confirmed using the measured extinction ratio of the plasmonic signals which are generated from the modulated optical signals, when compared to the extended radiation length calculated for a wide range of the input power. It is also shown that LRSPP transmission is sensitive to the excited power of edge plasmon in the gap through the permittivity change near the gap. Such a control of SPPs through the use of light could be boosted by the hybridized edge plasmon mode and a huge field enhancement using nanogap, gratings or metasurfaces, and could provide opportunities for ultrafast nano-plasmonic signal generation that is compatible with pervasive optical communication systems.
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5
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Ochs M, Zurak L, Krauss E, Meier J, Emmerling M, Kullock R, Hecht B. Nanoscale Electrical Excitation of Distinct Modes in Plasmonic Waveguides. NANO LETTERS 2021; 21:4225-4230. [PMID: 33929199 DOI: 10.1021/acs.nanolett.1c00182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The electrical excitation of guided plasmonic modes at the nanoscale enables integration of optical nanocircuitry into nanoelectronics. In this context, exciting plasmons with a distinct modal field profile constitutes a key advantage over conventional single-mode integrated photonics. Here, we demonstrate the selective electrical excitation of the lowest-order symmetric and antisymmetric plasmonic modes in a two-wire transmission line. We achieve mode selectivity by precisely positioning nanoscale excitation sources, i.e., junctions for inelastic electron tunneling, within the respective modal field distribution. By using advanced fabrication that combines focused He-ion beam milling and dielectrophoresis, we control the location of tunnel junctions with sub-10 nm accuracy. At the far end of the two-wire transmission line, the guided plasmonic modes are converted into far-field radiation at separate spatial positions showing two distinct orthogonal polarizations. Hence, the resulting device represents the smallest electrically driven light source with directly switchable polarization states with possible applications in display technology.
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Affiliation(s)
- Maximilian Ochs
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Luka Zurak
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Enno Krauss
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jessica Meier
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Monika Emmerling
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - René Kullock
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Bert Hecht
- NanoOptics & Biophotonics Group, Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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6
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Park SM, Lee KS, Kim JH, Yeon GJ, Shin HH, Park S, Kim ZH. Direct Visualization of Gap-Plasmon Propagation on a Near-Touching Nanowire Dimer. J Phys Chem Lett 2020; 11:9313-9320. [PMID: 33089991 DOI: 10.1021/acs.jpclett.0c02494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dimers of metallic nanowires (NWs) with nanometric gaps could be an alternative to overcome the limitations of existing plasmonic waveguides. The gap-surface plasmon polaritons (gap-SPPs) of the dimers may propagate along the NW without crosstalk and greatly enhance the coupling efficiency with an emitter, enabling ultracompact optical circuits. Such a possibility has not been realized, and we experimentally show its possibility. The gap-SPPs of the AgNW-molecule-AgNW structure, with a gap of 3-5 nm defined by the molecules, are visualized using the surface-enhanced Raman scattering (SERS) of the molecules. The SERS images, representing the gap-field intensity distribution, reveal the decay and beating of the monopole-monopole and dipole-dipole gap modes. The propagation lengths of the two (l1 = 0.5-2 μm and l2 = 5-8 μm) closely follow the model prediction with a uniform gap, confirming that the scattering loss induced by the gap irregularities is surprisingly low.
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Affiliation(s)
- Sang-Min Park
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Kang Sup Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Jin-Ho Kim
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Gyu Jin Yeon
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Hyun-Hang Shin
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Sangwon Park
- Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08826, Korea
| | - Zee Hwan Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
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7
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Chen TY, Tyagi D, Chang YC, Huang CB. A Polarization-Actuated Plasmonic Circulator. NANO LETTERS 2020; 20:7543-7549. [PMID: 32986442 DOI: 10.1021/acs.nanolett.0c03008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A circulator for surface plasmon polaritons (SPPs) based on a plasmonic two-wire transmission-line (TWTL) structure is experimentally realized. A TWTL offers two distinct plasmon modes that can be independently excited, solely determined by the polarization of the laser field. Through controlled superposition of the two modes, TWTLs are exploited to enable polarization-actuated plasmonic circulators. In the first demonstration, the coupling antennas to the plasmonic circulator are designed to circulate SPPs sensitive to linearly polarized excitation. In the second design, the circulator reacts to the spin angular momenta carried by circularly polarized laser excitations. In both cases, the SPP circulation directions are directly controlled by the laser polarization, and the number of ports is easily expandable. Experimentally, a wide optical operational bandwidth of ∼100 nm is achieved. The results show a major step toward the realization of multifunctioning photonic nanocircuitry.
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Affiliation(s)
- Tzu-Yu Chen
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Dhruv Tyagi
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yun-Chorng Chang
- Research Center for Applied Science, Academia Sinica, Nangang 11529, Taipei, Taiwan
| | - Chen-Bin Huang
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan
- Research Center for Applied Science, Academia Sinica, Nangang 11529, Taipei, Taiwan
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8
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Da Browski M, Dai Y, Petek H. Ultrafast Photoemission Electron Microscopy: Imaging Plasmons in Space and Time. Chem Rev 2020; 120:6247-6287. [PMID: 32530607 DOI: 10.1021/acs.chemrev.0c00146] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Plasmonics is a rapidly growing field spanning research and applications across chemistry, physics, optics, energy harvesting, and medicine. Ultrafast photoemission electron microscopy (PEEM) has demonstrated unprecedented power in the characterization of surface plasmons and other electronic excitations, as it uniquely combines the requisite spatial and temporal resolution, making it ideally suited for 3D space and time coherent imaging of the dynamical plasmonic phenomena on the nanofemto scale. The ability to visualize plasmonic fields evolving at the local speed of light on subwavelength scale with optical phase resolution illuminates old phenomena and opens new directions for growth of plasmonics research. In this review, we guide the reader thorough experimental description of PEEM as a characterization tool for both surface plasmon polaritons and localized plasmons and summarize the exciting progress it has opened by the ultrafast imaging of plasmonic phenomena on the nanofemto scale.
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Affiliation(s)
- Maciej Da Browski
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.,Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon EX4 4QL, U.K
| | - Yanan Dai
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Hrvoje Petek
- Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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9
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Chen TY, Obermeier J, Schumacher T, Lin FC, Huang JS, Lippitz M, Huang CB. Modal Symmetry Controlled Second-Harmonic Generation by Propagating Plasmons. NANO LETTERS 2019; 19:6424-6428. [PMID: 31442060 DOI: 10.1021/acs.nanolett.9b02630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A new concept for second-harmonic generation (SHG) in an optical nanocircuit is proposed. We demonstrate both theoretically and experimentally that the symmetry of an optical mode alone is sufficient to allow SHG even in centro-symmetric structures made of centro-symmetric material. The concept is realized using a plasmonic two-wire transmission-line (TWTL), which simultaneously supports a symmetric and an antisymmetric mode. We first confirm that emission of second-harmonic light into the symmetric mode of the waveguide is symmetry-allowed when the fundamental excited waveguide modes are either purely symmetric or antisymmetric. We further switch the emission into the antisymmetric mode when a controlled mixture of the fundamental modes is excited simultaneously. Our results open up a new degree of freedom into the designs of nonlinear optical components and should pave a new avenue toward multifunctional nanophotonic circuitry.
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Affiliation(s)
- Tzu-Yu Chen
- Institute of Photonics Technologies , National Tsing Hua University , Hsinchu 30013 , Taiwan
- International Intercollegiate PhD Program , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Julian Obermeier
- Department of Physics , University of Bayreuth , 95440 Bayreuth , Germany
| | | | - Fan-Cheng Lin
- Department of Chemistry , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Jer-Shing Huang
- Leibniz Institute of Photonic Technology , 07745 Jena , Germany
| | - Markus Lippitz
- Department of Physics , University of Bayreuth , 95440 Bayreuth , Germany
| | - Chen-Bin Huang
- Institute of Photonics Technologies , National Tsing Hua University , Hsinchu 30013 , Taiwan
- Research Center for Applied Sciences , Academia Sinica , Taipei 115-29 , Taiwan
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10
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Lin FC, See KM, Ouyang L, Huang YX, Chen YJ, Popp J, Huang JS. Designable Spectrometer-Free Index Sensing Using Plasmonic Doppler Gratings. Anal Chem 2019; 91:9382-9387. [PMID: 31329421 DOI: 10.1021/acs.analchem.9b02662] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Typical nanoparticle-based plasmonic index sensors detect the spectral shift of localized surface plasmon resonance (LSPR) upon the change of the environmental index. Therefore, they require broadband illumination and spectrometers. The sensitivity and flexibility of nanoparticle-based index sensors are usually limited because LSPR peaks are usually broad and the spectral position cannot be freely designed. Here, we present a fully designable index sensing platform using plasmonic Doppler gratings (PDGs), which provide broadband and azimuthal angle dependent grating periodicity. Different from LSPR sensors, PDG index sensors are based on the momentum matching between photons and surface plasmons via the lattice momentum of the grating. Therefore, the index change is translated into the variation of the in-plane azimuthal angle for photon-to-plasmon coupling, which manifests as directly observable dark bands in the reflection image. The PDG can be freely designed to optimally match the range of index variation for specific applications. In this work, we demonstrate PDG index sensors for large (n = 1.00-1.52) and small index variations (n = 1.3330-1.3650). The tiny and nonlinear index change of the water-ethanol mixture has been clearly observed and accurately quantified. Since the PDG is a dispersive device, it enables on-site and single-color index sensing without a spectrometer and provides a promising spectroscopic platform for on-chip analytical applications.
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Affiliation(s)
- Fan-Cheng Lin
- Department of Chemistry , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Kel-Meng See
- Department of Chemistry , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Lei Ouyang
- Leibniz Institute of Photonic Technology , Albert-Einstein Straße 9 , Jena D-07745 , Germany.,Institute of Physical Chemistry and Abbe Center of Photonics , Friedrich-Schiller-Universität Jena , Helmholtzweg 4 , Jena D-07743 , Germany
| | - You-Xin Huang
- Department of Chemistry , National Tsing Hua University , Hsinchu 30013 , Taiwan
| | - Yi-Ju Chen
- Leibniz Institute of Photonic Technology , Albert-Einstein Straße 9 , Jena D-07745 , Germany
| | - Jürgen Popp
- Leibniz Institute of Photonic Technology , Albert-Einstein Straße 9 , Jena D-07745 , Germany.,Institute of Physical Chemistry and Abbe Center of Photonics , Friedrich-Schiller-Universität Jena , Helmholtzweg 4 , Jena D-07743 , Germany
| | - Jer-Shing Huang
- Department of Chemistry , National Tsing Hua University , Hsinchu 30013 , Taiwan.,Leibniz Institute of Photonic Technology , Albert-Einstein Straße 9 , Jena D-07745 , Germany.,Research Center for Applied Sciences , Academia Sinica , 128 Sec. 2, Academia Road , Nankang District, Taipei 11529 , Taiwan.,Department of Electrophysics , National Chiao Tung University , Hsinchu 30010 , Taiwan
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11
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Schörner C, Adhikari S, Lippitz M. A Single-Crystalline Silver Plasmonic Circuit for Visible Quantum Emitters. NANO LETTERS 2019; 19:3238-3243. [PMID: 31009229 DOI: 10.1021/acs.nanolett.9b00773] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Plasmonic waveguides are key elements in nanophotonic devices, serving as optical interconnects between nanoscale light sources and detectors. Multimode operation in plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation and information encoding. However, highly confined plasmon propagation along gold nanostructures is typically limited to the near-infrared region due to ohmic losses, excluding all visible quantum emitters from plasmonic circuitry. We report on the top-down fabrication of complex plasmonic nanostructures in single-crystalline silver plates. We demonstrate the controlled remote excitation of a small ensemble of fluorophores by a set of waveguide modes and the emission of the visible luminescence into the waveguide with high efficiency. This approach opens up the study of a nanoscale light-matter interaction between complex plasmonic waveguides and a large variety of quantum emitters available in the visible spectral range.
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Affiliation(s)
- Christian Schörner
- Experimental Physics III , University of Bayreuth , D-95447 Bayreuth , Germany
| | - Subhasis Adhikari
- Experimental Physics III , University of Bayreuth , D-95447 Bayreuth , Germany
| | - Markus Lippitz
- Experimental Physics III , University of Bayreuth , D-95447 Bayreuth , Germany
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12
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Krauss E, Razinskas G, Köck D, Grossmann S, Hecht B. Reversible Mapping and Sorting the Spin of Photons on the Nanoscale: A Spin-Optical Nanodevice. NANO LETTERS 2019; 19:3364-3369. [PMID: 31013109 DOI: 10.1021/acs.nanolett.9b01162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The photon spin is an important resource for quantum information processing as is the electron spin in spintronics. However, for subwavelength confined optical excitations, polarization as a global property of a mode cannot be defined. Here, we show that any polarization state of a plane-wave photon can reversibly be mapped to a pseudospin embodied by the two fundamental modes of a subwavelength plasmonic two-wire transmission line. We design a device in which this pseudospin evolves in a well-defined fashion throughout the device reminiscent of the evolution of photon polarization in a birefringent medium and the behavior of electron spins in the channel of a spin field-effect transistor. The significance of this pseudospin is enriched by the fact that it is subject to spin-orbit locking. Combined with optically active materials to exert external control over the pseudospin precession, our findings could enable spin-optical transistors, that is, the routing and processing of quantum information with light on a subwavelength scale.
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Affiliation(s)
- Enno Krauss
- NanoOptics and Biophotonics Group, Experimental Physics 5 , University of Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Gary Razinskas
- NanoOptics and Biophotonics Group, Experimental Physics 5 , University of Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Dominik Köck
- NanoOptics and Biophotonics Group, Experimental Physics 5 , University of Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Swen Grossmann
- NanoOptics and Biophotonics Group, Experimental Physics 5 , University of Würzburg , Am Hubland, 97074 Würzburg , Germany
| | - Bert Hecht
- NanoOptics and Biophotonics Group, Experimental Physics 5 , University of Würzburg , Am Hubland, 97074 Würzburg , Germany
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13
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Wei H, Pan D, Zhang S, Li Z, Li Q, Liu N, Wang W, Xu H. Plasmon Waveguiding in Nanowires. Chem Rev 2018; 118:2882-2926. [DOI: 10.1021/acs.chemrev.7b00441] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Hong Wei
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Deng Pan
- School of Physics and Technology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Shunping Zhang
- School of Physics and Technology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Zhipeng Li
- Beijing Key Laboratory of Nano-Photonics and Nano-Structure (NPNS), Department of Physics, Capital Normal University, Beijing 100048, China
| | - Qiang Li
- Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006, China
| | - Ning Liu
- Department of Physics and Bernal Institute, University of Limerick, Limerick, Ireland
| | - Wenhui Wang
- School of Science, Xi’an Jiaotong University, Xi’an 710049, China
| | - Hongxing Xu
- School of Physics and Technology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China
- Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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14
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Wu X, Jiang P, Razinskas G, Huo Y, Zhang H, Kamp M, Rastelli A, Schmidt OG, Hecht B, Lindfors K, Lippitz M. On-Chip Single-Plasmon Nanocircuit Driven by a Self-Assembled Quantum Dot. NANO LETTERS 2017; 17:4291-4296. [PMID: 28590750 DOI: 10.1021/acs.nanolett.7b01284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Quantum photonics holds great promise for future technologies such as secure communication, quantum computation, quantum simulation, and quantum metrology. An outstanding challenge for quantum photonics is to develop scalable miniature circuits that integrate single-photon sources, linear optical components, and detectors on a chip. Plasmonic nanocircuits will play essential roles in such developments. However, for quantum plasmonic circuits, integration of stable, bright, and narrow-band single photon sources in the structure has so far not been reported. Here we present a plasmonic nanocircuit driven by a self-assembled GaAs quantum dot. Through a planar dielectric-plasmonic hybrid waveguide, the quantum dot efficiently excites narrow-band single plasmons that are guided in a two-wire transmission line until they are converted into single photons by an optical antenna. Our work demonstrates the feasibility of fully on-chip plasmonic nanocircuits for quantum optical applications.
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Affiliation(s)
- Xiaofei Wu
- Experimental Physics III, University of Bayreuth , Universitätsstraße 30, 95447 Bayreuth, Germany
- Max-Planck-Institute for Solid State Research , Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Ping Jiang
- Experimental Physics III, University of Bayreuth , Universitätsstraße 30, 95447 Bayreuth, Germany
- College of Science, China University of Petroleum , Changjiang West Road 66, Qingdao 266580, China
| | | | - Yongheng Huo
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Hongyi Zhang
- Max-Planck-Institute for Solid State Research , Heisenbergstraße 1, 70569 Stuttgart, Germany
| | | | - Armando Rastelli
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | - Oliver G Schmidt
- Institute for Integrative Nanosciences, IFW Dresden , Helmholtzstraße 20, 01069 Dresden, Germany
| | | | - Klas Lindfors
- Max-Planck-Institute for Solid State Research , Heisenbergstraße 1, 70569 Stuttgart, Germany
- Department of Chemistry, University of Cologne , Luxemburger Straße 116, 50939 Köln, Germany
| | - Markus Lippitz
- Experimental Physics III, University of Bayreuth , Universitätsstraße 30, 95447 Bayreuth, Germany
- Max-Planck-Institute for Solid State Research , Heisenbergstraße 1, 70569 Stuttgart, Germany
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15
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Huang CB(R. Optical Metasurface for the Creation and Applications of Surface Plasmon Vortices. JSAP-OSA JOINT SYMPOSIA 2017 ABSTRACTS 2017. [DOI: 10.1364/jsap.2017.8a_a409_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Optical vortices are waves carrying orbital angular momentum and exhibit helical phase fronts. Helical phase front leads to discontinuous azimuthal phase jumps and the number of phase discontinuities (abrupt phase jumps from −π to π) within a 2π range is referred to as the topological charge of an optical vortex. Optical vortices have been applied in trapping and spinning of microparticles, and recently in free-space data transmission. Generation of optical beams carrying orbital angular momentum has received increasing attentions recently, both in the far-field and in the near-field. Near-field vortices are typically generated through the excitation of surface plasmons (SP). However, the intensity patterns of the SP vortices generated thus far, just like the free-space vortex beams, are all azimuthally symmetrical (annular) since mathematically they conform to the Bessel function.
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16
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Ohana D, Desiatov B, Mazurski N, Levy U. Dielectric Metasurface as a Platform for Spatial Mode Conversion in Nanoscale Waveguides. NANO LETTERS 2016; 16:7956-7961. [PMID: 27960507 DOI: 10.1021/acs.nanolett.6b04264] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We experimentally demonstrate a nanoscale mode converter that performs coupling between the first two transverse electric-like modes of a silicon-on-insulator waveguide. The device operates by introducing a nanoscale periodic perturbation in its effective refractive index along the propagation direction and a graded effective index profile along its transverse direction. The periodic perturbation provides phase matching between the modes, while the graded index profile, which is realized by the implementation of nanoscale dielectric metasurface consisting of silicon features that are etched into the waveguide taking advantage of the effective medium concept, provides the overlap between the modes. Following the device design and numerical analysis using three-dimensional finite difference time domain simulations, we have fabricated the device and characterized it by directly measuring the modal content using optical imaging microscopy. From these measurements, the mode purity is estimated to be 95% and the transmission relative to an unperturbed strip waveguide is as high as 88%. Finally, we extend this approach to accommodate for the coupling between photonic and plasmonic modes. Specifically, we design and numerically demonstrate photonic to plasmonic mode conversion in a hybrid waveguide in which photonic and surface plasmon polariton modes can be guided in the silicon core and in the silicon/metal interface, respectively. The same method can also be used for coupling between symmetric and antisymmetric plasmonic modes in metal-insulator-metal or insulator-metal-insulator structures. On the basis of the current demonstration, we believe that such nanoscale dielectric metasurface-based mode converters can now be realized and become an important building block in future nanoscale photonic and plasmonic devices. Furthermore, the demonstrated platform can be used for the implementation of other chip scale components such as splitters, combiners couplers, and more.
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Affiliation(s)
- David Ohana
- Department of Applied Physics, The Benin School of Engineering and Computer Science, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem, 91904, Israel
| | - Boris Desiatov
- Department of Applied Physics, The Benin School of Engineering and Computer Science, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem, 91904, Israel
| | - Noa Mazurski
- Department of Applied Physics, The Benin School of Engineering and Computer Science, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem, 91904, Israel
| | - Uriel Levy
- Department of Applied Physics, The Benin School of Engineering and Computer Science, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem, 91904, Israel
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17
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Chang CW, Lin CE, Yu CJ, Yeh TT, Yen TJ. Miniature Surface Plasmon Polariton Amplitude Modulator by Beat Frequency and Polarization Control. Sci Rep 2016; 6:32098. [PMID: 27558516 PMCID: PMC4997335 DOI: 10.1038/srep32098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/02/2016] [Indexed: 11/09/2022] Open
Abstract
The miniaturization of modulators keeps pace for the compact devices in optical applications. Here, we present a miniature surface plasmon polariton amplitude modulator (SPPAM) by directing and interfering surface plasmon polaritons on a nanofabricated chip. Our results show that this SPPAM enables two kinds of modulations. The first kind of modulation is controlled by encoding angular-frequency difference from a Zeeman laser, with a beat frequency of 1.66 MHz; the second of modulation is validated by periodically varying the polarization states from a polarization generator, with rotation frequencies of 0.5–10 k Hz. In addition, the normalized extinction ratio of our plasmonic structure reaches 100. Such miniaturized beat-frequency and polarization-controlled amplitude modulators open an avenue for the exploration of ultrasensitive nanosensors, nanocircuits, and other integrated nanophotonic devices.
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Affiliation(s)
- Cheng-Wei Chang
- Department of Materials Science and Engineering, National Tsing Hua University, 101, Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan
| | - Chu-En Lin
- Department of Mechanical Engineering, National Chin-Yi University of Technology, Taichung 41170, Taiwan
| | - Chih-Jen Yu
- Graduate Institute of Electro-Optical Engineering, Chang Gung University, Taoyuan 333, Taiwan
| | - Ting-Tso Yeh
- Department of Materials Science and Engineering, National Tsing Hua University, 101, Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan
| | - Ta-Jen Yen
- Department of Materials Science and Engineering, National Tsing Hua University, 101, Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan.,Center for Nanotechnology, Materials Science, and Microsystems, National Tsing Hua University., 101, Section 2 Kuang Fu Road, Hsinchu 30013, Taiwan
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18
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Johns P, Yu K, Devadas MS, Hartland GV. Role of Resonances in the Transmission of Surface Plasmon Polaritons between Nanostructures. ACS NANO 2016; 10:3375-3381. [PMID: 26866536 DOI: 10.1021/acsnano.5b07185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding how surface plasmon polaritons (SPPs) propagate in metal nanostructures is important for the development of plasmonic devices. In this paper, we study the transmission of SPPs between single-crystal gold nanobars on a glass substrate using transient absorption microscopy. The coupled structures were produced by creating gaps in single nanobars by focused ion beam milling. SPPs were launched by focusing the pump laser at the end of the nanobar, and the transmission across the gaps was imaged by scanning the probe laser over the nanostructure. The results show larger losses at small gap sizes. Finite element method calculations were used to investigate this effect. The calculations show two main modes for nanobars on a glass surface: a leaky mode localized at the air-gold interface, and a bound mode localized at the glass-gold interface. At specific gap sizes (approximately 50 nm for our system), these SPP modes can excite localized surface plasmon modes associated with the gap, which dissipate energy. This increases the energy losses at small gap sizes. Experiments and simulations were also performed for the nanobars in microscope immersion oil, which creates a more homogeneous optical environment, and consistent results were observed.
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Affiliation(s)
- Paul Johns
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Kuai Yu
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Mary Sajini Devadas
- Department of Chemistry, Towson University , Towson, Maryland 21252, United States
| | - Gregory V Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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19
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Hoffmann B, Bashouti MY, Feichtner T, Mačković M, Dieker C, Salaheldin AM, Richter P, Gordan OD, Zahn DRT, Spiecker E, Christiansen S. New insights into colloidal gold flakes: structural investigation, micro-ellipsometry and thinning procedure towards ultrathin monocrystalline layers. NANOSCALE 2016; 8:4529-4536. [PMID: 26661036 DOI: 10.1039/c5nr04439a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
High-quality fabrication of plasmonic devices often relies on wet-chemically grown ultraflat, presumably single-crystalline gold flakes due to their superior materials properties. However, important details about their intrinsic structure and their optical properties are not well understood yet. In this study, we present a synthesis routine for large flakes with diameters of up to 70 μm and an in-depth investigation of their structural and optical properties. The flakes are precisely analyzed by transmission electron microscopy, electron backscatter diffraction and micro-ellipsometry. We found new evidence for the existence of twins extending parallel to the Au flake {111} surfaces which have been found to not interfere with the presented nanopatterning. Micro-Ellipsometry was carried out to determine the complex dielectric function and to compare it to previous measurements of bulk single crystalline gold. Finally, we used focused ion beam milling to prepare smooth crystalline layers and high-quality nanostructures with desired thickness down to 10 nm to demonstrate the outstanding properties of the flakes. Our findings support the plasmonics and nano optics community with a better understanding of this material which is ideally suited for superior plasmonic nanostructures.
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Affiliation(s)
- B Hoffmann
- Max Planck Institute for the Science of Light, D-91058 Erlangen, Germany.
| | - M Y Bashouti
- Max Planck Institute for the Science of Light, D-91058 Erlangen, Germany.
| | - T Feichtner
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany and Max Planck Institute for the Science of Light, D-91058 Erlangen, Germany.
| | - M Mačković
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Mikro- und Nanostrukturforschung (WW9) & Center for Nanoanalysis and Electron Microscopy, Department Werkstoffwissenschaften, D-91058 Erlangen, Germany
| | - C Dieker
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Mikro- und Nanostrukturforschung (WW9) & Center for Nanoanalysis and Electron Microscopy, Department Werkstoffwissenschaften, D-91058 Erlangen, Germany
| | - A M Salaheldin
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Institute of Particle Technology, D-91058 Erlangen, Germany
| | - P Richter
- Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
| | - O D Gordan
- Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
| | - D R T Zahn
- Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany
| | - E Spiecker
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Mikro- und Nanostrukturforschung (WW9) & Center for Nanoanalysis and Electron Microscopy, Department Werkstoffwissenschaften, D-91058 Erlangen, Germany
| | - S Christiansen
- Helmholtz Zentrum Berlin für Materialien und Energie GmbH, D-14109 Berlin, Germany and Max Planck Institute for the Science of Light, D-91058 Erlangen, Germany.
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20
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Broadband nanophotonic wireless links and networks using on-chip integrated plasmonic antennas. Sci Rep 2016; 6:19490. [PMID: 26783033 PMCID: PMC4725999 DOI: 10.1038/srep19490] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 12/14/2015] [Indexed: 11/25/2022] Open
Abstract
Owing to their high capacity and flexibility, broadband wireless communications have been widely employed in radio and microwave regimes, playing indispensable roles in our daily life. Their optical analogs, however, have not been demonstrated at the nanoscale. In this paper, by exploiting plasmonic nanoantennas, we demonstrate the complete design of broadband wireless links and networks in the realm of nanophotonics. With a 100-fold enhancement in power transfer superior to previous designs as well as an ultrawide bandwidth that covers the entire telecommunication wavelength range, such broadband nanolinks and networks are expected to pave the way for future optical integrated nanocircuits.
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21
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Liu HW, Lin FC, Lin SW, Wu JY, Chou BT, Lai KJ, Lin SD, Huang JS. Single-Crystalline Aluminum Nanostructures on a Semiconducting GaAs Substrate for Ultraviolet to Near-Infrared Plasmonics. ACS NANO 2015; 9:3875-3886. [PMID: 25848830 DOI: 10.1021/nn5070887] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and is superior to noble metals in natural abundance, cost, and compatibility with modern semiconductor fabrication processes. Ultrasmooth single-crystalline metallic films are beneficial for the fabrication of high-definition plasmonic nanostructures, especially complex integrated nanocircuits. The absence of surface corrugation and crystal boundaries also guarantees superior optical properties and applications in nanolasers. Here, we present UV to near-infrared plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam milling into an ultrasmooth single-crystalline aluminum film grown on a semiconducting GaAs substrate with a molecular beam epitaxy method. The single-crystalline aluminum film shows improved reflectivity and reduced two-photon photoluminescence (TPPL) due to the ultrasmooth surface. Both linear scattering and nonlinear TPPL are studied in detail. The nanoslit arrays show clear Fano-like resonance, and the nanoholes are found to support both photonic modes and localized surface plasmon resonance. We also found that TPPL generation is more efficient when the excitation polarization is parallel rather than perpendicular to the edge of the aluminum film. Such a counterintuitive phenomenon is attributed to the high refractive index of the GaAs substrate. We show that the polarization of TPPL from aluminum preserves the excitation polarization and is independent of the crystal orientation of the film or substrate. Our study gains insight into the optical property of aluminum nanostructures on a high-index semiconducting GaAs substrate and illustrates a practical route to implement plasmonic devices onto semiconductors for future hybrid nanodevices.
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Affiliation(s)
- Hsuan-Wei Liu
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Fan-Cheng Lin
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Shi-Wei Lin
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Jau-Yang Wu
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Bo-Tsun Chou
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Kuang-Jen Lai
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Sheng-Di Lin
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
| | - Jer-Shing Huang
- †Department of Electronics Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
- ‡Department of Chemistry, and §Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30010, Taiwan
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22
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Kim J, Lee SY, Park H, Lee K, Lee B. Reflectionless compact plasmonic waveguide mode converter by using a mode-selective cavity. OPTICS EXPRESS 2015; 23:9004-9013. [PMID: 25968736 DOI: 10.1364/oe.23.009004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A compact transmissive plasmonic waveguide mode converter which aims for the elimination of reflection and transmission of unconverted mode is proposed. The proposed scheme exploits a cavity formed by mode selective mirrors, which only allows two output modes: the transmission of the target mode and the reflection of the input mode. By appropriately tuning cavity lengths, the reflection of the input mode can also be suppressed to near zero by destructive interference, thereby all the residual outgoing modes are suppressed. The proposed device might be useful in the design of integrated photonic system since it relaxes the problem of unwanted reflection.
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23
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Johns P, Yu K, Devadas MS, Li Z, Major TA, Hartland GV. Effect of substrate discontinuities on the propagating surface plasmon polariton modes in gold nanobars. NANOSCALE 2014; 6:14289-14296. [PMID: 25321926 DOI: 10.1039/c4nr04131c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The surface plasmon polariton (SPP) modes of gold nanobars (nanowires with rectangular dimensions) have been investigated by scanning pump-probe microscopy. In these experiments the nanobars were suspended over trenches cut in glass coverslips, and propagating SPP modes were launched in the supported portion of the nanobar by focusing a near-IR pump laser beam at the end of the nanobar. Transient absorption images were then collected by scanning the probe laser over the nanobar using a galvo-mirror system. The images show that the trench has a large effect on the SPP modes, specifically, for approximately half the nanowires the propagation length is significantly reduced after the trench. Finite element calculations were performed to understand this effect. The calculations show that the pump laser excites bound and leaky modes (modes that have their fields localized at the nanobar/glass or nanobar/air interfaces, respectively) in the supported portions of the nanobars. These modes propagate along the nanobar. When they meet the trench their field distributions are altered. The modes that derive from the bound mode are strongly damped over the trench. Thus, the bound mode is not reconstituted on the opposite side of the trench, and only the leaky mode contributes to the signal. Because the bound and leaky modes can have different propagation lengths, the propagation lengths measured in our experiments can change from one side of the trench to the other. The results show how the substrate can be engineered to control the SPP modes in metal nanostructures.
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Affiliation(s)
- Paul Johns
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
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24
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Sinha AK, Sasmal AK, Mehetor SK, Pradhan M, Pal T. Evolution of amorphous selenium nanoballs in silicone oil and their solvent induced morphological transformation. Chem Commun (Camb) 2014; 50:15733-6. [DOI: 10.1039/c4cc08168d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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