The combination of optical, electronic and mechanical effects occurring in devices and materials that have structure on the nanometer scale are being investigated by researchers around the world. These "collective phenomena" have applications as diverse as the generation of light, optical sensing, and information processing. To highlight the recent progress and trends in physics and applications in this area, the editors of the Optical Society's (OSA) open-access journal Optics Express (http://www.opticsinfobase.org/oe) today published a special focus issue on "Collective Phenomena in Photonic, Plasmonic and Hybrid Structures." The issue is organized and edited by Guest Editors Svetlana V. Boriskina of Boston University, Michelle Povinelli of the University of Southern California, Vasily N. Astratov of the University of North Carolina at Charlotte, Anatoly V. Zayats of King's College London, and Viktor A. Podolskiy of the University of Massachusetts Lowell.
Photonic and plasmonic nanostructures provide exciting opportunities for trapping and manipulating light in volumes that can be even smaller than the wavelength of light. These effects have already been harnessed for applications in optical communications, energy generation and biomedical research. The next challenge faced by researchers in this burgeoning field is the understanding and exploiting of collective phenomena — phenomena due to the interactions of the individual photonic, plasmonic, electronic and mechanical components. Examples of this include a small object that starts to vibrate by shining light on it, or an artificial nano-structured material whose optical and electronic properties result from the concerted action of its individual building blocks.
"Our goal in publishing this focus issue is to spur further inter-disciplinary research merging nanophotonics, plasmonics, optomechanics and material science, which could lead to the development of novel classes of high-performance devices and nano-structured materials with custom-designed optical, electronic and mechanical characteristics," said Boriskina.
The papers in this issue focus on studying the fundamental physics of collective phenomena due to the coupling of confined photonic, plasmonic, electronic and mechanical states, and in exploiting these phenomena to engineer novel devices for light generation, optical sensing, and information processing. The scattering, radiative and mechanical properties of structures and materials dominated by collective phenomena can differ significantly from those of individual components. Additional degrees of freedom offered by complex heterogeneous nanostructures can be used to obtain new device functionality through coupling-induced tailored control of fundamental physical processes.
Key Findings & Select Papers
Mark Stockman of Georgia State University (USA) provides a comprehensive review of recent advances in nanoplasmonics with a special emphasis on ultrafast, active and gain plasmonics. After reviewing the fundamentals of hot spots formation in plasmonic structures and arrays, the author focuses on the description of the mechanisms of spatiotemporal control of nanolocalization of optical energy. The principle of operation and applications of the active plasmonic element – spaser (Surface Plasmon Amplification by Stimulated Emission of Radiation) – are also discussed. Finally, the author summarizes possible ways to bypass, mitigate, or overcome dissipative losses inherent to nanoplasmonic networks, with the main focus on the Ohmic loss compensation by gain in photonic-plasmonic metamaterials. Paper: "Nanoplasmonics: Past, Present, and Glimpse into Future,"
A group of researchers from the CIC nanoGune Consolider, Centro de Física de Materiales, and Basque Fondation for Science, Spain, present a hybrid system consisting of cyanine dye J-aggregates and Ag nanoparticles attached to a spherical dielectric microcavity. Melnikau et al demonstrate that attractive optical properties of J-aggregates – such as narrow luminescence bands, high spontaneous emission rate, and giant third-order nonlinear susceptibility – can be further enhanced by the concerted action of the high-Q localized optical states in the microcavity and localized surface plasmon oscillations on noble-metal nanoparticles. The authors describe the method to form thin shells of J-aggregates and multi-layers consisting of J-aggregates and Ag nanoparticles on the surfaces of optical microspheres. This creative fabrication approach results in the experimental demonstration of cavity-assisted luminescence enhancement, enhanced Raman scattering, and polarization-sensitive mode damping caused by re-absorption of J-aggregate emission. It also opens many new possibilities for creating new photonic structures and materials with localized states in the optical spectrum and nonlinear optical response. Paper: "Whispering gallery mode resonators with J-aggregates,"
Researchers from Boston University introduce a new approach to realize active spatio-temporal control of light on the nanoscale, which is a major challenge in conventional plasmonic nanocircuitry. Boriskina and Reinhard propose to exploit the rich phase landscape of the near-field of high-Q optical microcavities to manipulate sub-wavelength spatial light distribution in nanoscale plasmonic structures. Their theoretical analysis reveals that the flow of light through plasmonic nanocircuits can be directed and reversibly switched via controllable activation of areas of circulating powerflow (optical vortices), whose positions and mutual coupling can be dynamically controlled by the excitation wavelength, polarization, and modulation of the microcavity refractive index. This research opens new opportunities for the development of locally-addressable vortex-operated switching architectures for quantum information nanocircuit and bio(chemical) sensing platforms. Paper: "Adaptive on-chip control of nano-optical fields with optoplasmonic vortex nanogates,"
A research group from the Yale University demonstrates wheel-shaped optomechanical resonators that operate at GHz frequency with high mechanical Q factor in ambient air. Fabricated on a CMOS-compatible all-integrated Si photonics platform, the devices feature high-finesse optical whispering gallery modes (loaded optical Q factor above 500,000), which allows for efficient transduction of their mechanical modes with high mechanical Q factors. Sun and colleagues demonstrate the mechanical mode Q-factors up to 4,000, which helps to improve the readout sensitivity and the coherence time of the mechanical vibration. The demonstrated GHz-frequency operation of the optomechanical device opens the way for developing high-speed sensing systems, routing signals of different frequencies in optical channels, and also for facilitating access to the quantum regime. Paper: "GHz optomechanical resonators with high mechanical Q factor in air,"