Session Chair: Hou-Tong Chen, Los Alamos National Laboratory Session Chair: Nicholas X. Fang, Massachusetts Institute of Technology
10:30am - 10:45am Oral
Utilizing of Holographic Principles in Surface Plasmons Excitation
Alexander M. MERZLIKIN1,2, Anton I. IGNATOV1
1All-Russia Research Institute of Automatics, Russian Federation; 2Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, Russian Federation
One of the actively developing fields of integrated optics is optics of surface plasmon waves for signal transmission and control. Plasmonic waveguides have been studied in a rather large number of theoretical and experimental works, in which degree of transverse localization of the plasmon waveguide mode, its propagation length (determined by losses of different kinds), and possibilities of increasing of the propagation length by adding active components were considered. Characteristics of various elements of integrated plasmonics based on such waveguides (bent waveguides, waveguide resonators, couplers, filters, etc.) were also examined.
Studies and applications of waveguides with high degree of transverse mode localization encounter the problem of efficient mode excitation with far field. This difficulty is caused by the mismatch between the field distribution of the waveguide mode, which is localized on a subwavelength scale, and the field of the exciting radiation, the transverse localization of which is not less than a few wavelengths. The problem of efficient optical excitation of plasmonic waveguides is still far from final solution.
In this report we present the investigation of application of the holographic principle to excitation of various plasmonic nanostructures, in particular to excitation of plasmonic waveguides. We show that the excitation by use of surface or volume holograms can be several times more efficient than usage of excitation systems based on periodic diffraction gratings. Holograms help us to get the best phase matching and thus they help to match the field distribution of the waveguide mode with the field distribution of the incident wave.
10:45am - 11:00am Oral
Active Multifunctional MEMS Metadevices
Longqing CONG, Prakash PITCHAPPA, Ranjan SINGH
Nanyang Technological University, Singapore
Metasurfaces have provided a novel route to control the local phase of electromagnetic radiation through subwavelength scatterers where the properties of each element remain passive. A passive metasurface design can only achieve a specific functionality as it is extremely challenging to reconfigure each element that contributes toward the control of the radiation. In this work, the authors propose a different scheme based on microelectromechanical system (MEMS) to reconfigure the resonance and radiation phase via control of each dipolar element. The suspension angle of the individual bimorph cantilever in air can be precisely controlled through electrostatic actuation that determines the operative phase diagram of the metadevice. The dynamic polarization conversion is demonstrated through global control. In addition, it is proposed that a multifunctional operation such as dynamic wavefront deflection and rewritable holographic display can be accomplished by using 1D and 2D control of the cantilever array when each cantilever in the MEMS metadevice array is uniformly and accurately controlled in the large-area samples. Such a rewritable proposition can enable myriad of applications of MEMS-based metadevices in polarization-division multiplexing and dynamic flat lenses.
11:00am - 11:30am Invited
Active Plasmon Switching
Department of Physics, The Chinese University of Hong Kong, Hong Kong S.A.R. (China)
Colloidal plasmonic nanocrystals have proven to be of enormous potential in a wide range of applications. To fully realize their technological potential and further explore their fundamental plasmonic properties relies on the ready availability of high-quality, high-performance nanocrystals. We have made tremendous efforts on the development of synthetic methods for colloidal metal nanocrystals. We have been able to synthesize highly uniform colloidal Au and Ag nanocrystals, including Au nanospheres, nanorods, nanobipyramids, nanoplates, Ag nanorods, and Au-based bimetallic nanostructures. Their localized plasmon energies can be readily varied from the visible to near-infrared regions. Recently, active plasmon control has received increasing attention. Successful attempts to achieve plasmonic switching have been demonstrated by integrating metal nanostructures with active media whose dielectric functions can be varied by external stimuli. Electroactive materials are particularly appealing, because they allow for a fast switching of plasmon under electrochemical stimuli, opening the door to technological applications in electrochromic smart windows, three-dimensional and flat-panel displays. We have been able to coat polyaniline onto Au nanocrystals in controllable shell thicknesses. The plasmon resonance of the Au core can be modulated reversibly by varying the dielectric function of the polyaniline shell through proton doping and dedoping. A scattering intensity modulation depth of ~10 dB is obtained for the plasmonic switching on the single core@shell nanostructures. The plasmonic switching is accompanied with more than 100 nm in the reversible plasmon peak shift. We have further realized electrochemical switching. In the single-particle electrochemical switching measurements, reversible plasmonic shifts of ~20 and ~100 nm are obtained on the coated Au nanospheres and nanorods, with a remarkable stability over 200 cycles. The plasmon energy can be precisely controlled within the shift range, with the plasmonic switching time being less than 10 ms. The ensemble coated Au nanocrystals also exhibit good electrochemical plasmonic switching performances.
11:30am - 12:00pm Invited
Plasmonic Metasurfaces: Active Functions Beyond Simple Electric-Field Enhancement
National Institute for Materials Science, Japan
Plasmonic metasurfaces offer practical forms for various applications such as light-wave manipulations, molecular sensing, unconventional light–matter interaction, and thermal emission. Recently, we experimentally demonstrated high-efficient molecular sensing platforms based on plasmo-photonic metasurfaces and plasmonic-cavity-array metasurfaces that are able to selectively enhance magnetic-dipole emission in rare-earth Er ions. The progress will be presented. Furthermore, we very recently found that plasmonic metasurfaces are able to extract III-V semiconductor quantum-dot emissions in a superlinear manner even under weak photoexcitation. This means that the plasmonic systems actively contribute to increase populations of the luminescent states through unconventional process. We address these active functions of plasmonic metasurfaces that have been found in recent experiment and are described in a scheme beyond simple electric-field enhancement.