Optical nanoantennas, i.e., elements transforming localized light or waveguide modes into freely propagating fields and vice versa, are vital components for modern nanophotonics. Optical antennas have been demonstrated to cause the Dicke superradiance effect, i.e., collective spontaneous emission of quantum sources. However, the impact of coherent excitation on the antenna performance, such as directivity, efficiency, and Purcell effect, remains mostly unexplored. Herein, using full-wave numerical simulations backed by a quantum model, we unveil that coherent excitation allows controlling antenna multipoles, on-demand excitation of nonradiative states, enhanced directivity and improves antenna radiation efficiency. This collective excitation corresponds to the states with nonzero dipole moment in the quantum picture, where the quantum phase is well defined. The results of this work bring another degree of freedom - the collective phase of an ensemble of quantum emitters - to control optical nanoantennas and, as such, pave the way to the use of collective excitations for nanophotonic devices with superb performance. To make the discussion independent of the frequency range, we consider the all-dielectric design and use dimensionless units.
Nanoantennas are efficient devices exhibiting large confined electric field enhancements. So far, they have been extensively researched mainly in the receiving mode, which means that the illuminating field is essentially a plane wave. In this paper, we consider the problem of designing an efficient and highly directive transmitting Nanoantenna where the system is energized by a non-plane wave field, a subwavelength laser excitation. Including short-wavelength components allowed us to achieve a 200-nm spot radius, which is a quarter of its incident wavelength (800 nm). Near- and far-field anten…
Momentum microscopy of ultrafast electron emission from a strongly driven optical nanoantenna
Carl von Ossietzky Universität Oldenburg（奥尔登堡卡尔·冯·奥西茨基大学）；ELI ALPS, The Extreme Light Infrastructure ERIC（ELI ALPS，极端光基础设施ERIC）；Leibniz Institute of Photonic Technology（莱布尼兹光子技术研究所）；Universität Würzburg（维尔茨堡大学）；Friedrich-Schiller-Universität Jena（耶拿弗里德里希·席勒大学）；HUN-REN Wigner Research Center for Physics（匈牙利科学院Wigner物理研究中心）
Optical-field emission from nanostructured solids such as subwavelength nanoantennas can be leveraged to create sub-femtosecond, PHz-scale electronics for optical-field detection. One application that is of particular interest is the detection of an incident optical pulse's carrier-envelope phase. Such carrier-envelope-phase detection requires few-cycle, broadband optical excitation where the resonant properties of the nanoantenna can strongly alter the response of the near field in time. Little quantitative investigation has been performed to understand how the geometry and resonant propertie…
Given the quasi-static nature of optical-field emission and the nontrivial dependence of the emission rate on the instantaneous electric field strength, the CEP-sensitive component of the emitted photocurrent is highly sensitive to the energy of the optical pulse, and should carry information about the underlying sub-cycle dynamics of electron emission. Here we examine CEP-sensitive photoemission from plasmonic gold nanoantennas excited with few-cycle optical pulses of increasing energy. We observe antiresonance-like features in the CEP-sensitive photocurrent; specifically, at a critical pulse…
Enhancing magneto-optical effects is crucial for size reduction of key photonic devices based on non-reciprocal propagation of light and to enable active nanophotonics. We disclose a so far unexplored approach that exploits dark plasmons to produce an unprecedented amplification of magneto-optical activity. We designed and fabricated non-concentric magnetoplasmonic-disk/plasmonic-ring-resonator nanocavities supporting multipolar dark modes. The broken geometrical symmetry of the design enables coupling with free-space light and hybridization of dark modes of the ring nanoresonator with the dip…
Analogous to radio- and microwave antennas, optical nanoantennas are devices that receive and emit radiation at optical frequencies. Until recently, the realization of electrically driven optical antennas was an outstanding challenge in nanophotonics. In this review we discuss and analyze recent reports in which quantum tunneling-specifically inelastic electron tunneling-is harnessed as a means to convert electrical energy into photons, mediated by optical antennas. To aid this analysis we introduce the fundamentals of optical antennas and inelastic electron tunneling. Our discussion is focuse…
In this work, we investigate multiphoton and optical-field tunneling emission from metallic surfaces with nanoscale vacuum gaps. Using time-dependent Schrodinger equation (TDSE) simulations, we find that the properties of the emitted photocurrent in such systems can be greatly altered by the application of only a few-volt DC bias. We find that when coupled with expected plasmonic enhancements within the nanometer-scale metallic gaps, the application of this DC bias significantly reduces the threshold for the transition to optical-field-driven tunneling from the metal surface, and could suffici…
Ultrafast light-matter interactions lead to optical-field-driven photocurrents with an attosecond-level temporal response. These photocurrents can be used to detect the carrier-envelope-phase (CEP) of short optical pulses, and could be utilized to create optical-frequency, petahertz (PHz) electronics for information processing. Despite recent reports on optical-field-driven photocurrents in various nanoscale solid-state materials, little has been done in examining the large-scale integration of these devices. In this work, we demonstrate enhanced, on-chip CEP detection via optical-field-driven…
The ever-growing field of microfluidics requires precise and flexible control over fluid flow at the micro- and nanoscales. Current constraints demand a variety of controllable components for performing different operations inside closed microchambers and microreactors. In this context, novel nanophotonic approaches can significantly enhance existing capabilities and provide new functionalities via finely tuned light-matter interaction mechanisms. Here we propose a novel design, featuring a dual functionality on-chip: boosted optically-driven particle diffusion and nanoparticle sorting. Our me…
