Optical Rectification and Field Enhancement in a Plasmonic Nanogap

Abstract

Metal nanostructures act as powerful optical antennas[1, 2] because collective modes of the electron fluid in the metal are excited when light strikes the surface of the nanostructure. These excitations, known as plasmons, can have evanescent electromagnetic fields that are orders of magnitude larger than the incident electromagnetic field. The largest field enhancements often occur in nanogaps between plasmonically active nanostructures[3, 4], but it is extremely challenging to measure the fields in such gaps directly. These enhanced fields have applications in surface-enhanced spectroscopies[5-7], nonlinear optics[1, 8-10], and nanophotonics[11-15]. Here we show that nonlinear tunnelling conduction between gold electrodes separated by a subnanometre gap leads to optical rectification, producing a DC photocurrent when the gap is illuminated. Comparing this photocurrent with low frequency conduction measurements, we determine the optical frequency voltage across the tunnelling region of the nanogap, and also the enhancement of the electric field in the tunnelling region, as a function of gap size. The measured field enhancements exceed 1000, consistent with estimates from surface-enhanced Raman measurements[16-18]. Our results highlight the need for more realistic theoretical approaches that are able to model the electromagnetic response of metal nanostructures on scales ranging from the free space wavelength, $\lambda$, down to $\sim \lambda /1000$, and for experiments with new materials, different wavelengths, and different incident polarizations.

15 pages, 5 figures + 12 pages, 5 figures of supplemental information

References in corpus (7)

• Electromigrated nanoscale gaps for surface-enhanced Raman spectroscopy
• Simultaneous measurements of electronic conduction and Raman response in molecular junctions
• Cluster-based density-functional approach to quantum transport through molecular and atomic contacts
• Effects of Quantum Tunneling in Metal Nano-gap on Surface-Enhanced Raman Scattering
• Influence of chopped laser light onto the electronic transport through atomic-sized contacts
• Electronic and optical properties of electromigrated molecular junctions
• Role of electronic structure in photoassisted transport through atomic-sized contacts

Cited by in corpus (49)

• Nanoantennas for visible and infrared radiation
• Generalized nonlocal optical response in nanoplasmonics
• Antenna-coupled photon emission from hexagonal boron nitride tunnel junctions
• Ab-initio nanoplasmonics: The impact of atomic structure
• Atomic-scale confinement of optical fields
• Thermoplasmonics: Quantifying plasmonic heating in single nanowires
• Spontaneous hot-electron light emission from electron-fed optical antennas
• Tunnel field-effect transistors for sensitive terahertz detection
• Dark plasmons in hot spot generation and polarization in interelectrode nanoscale junctions
• Nonlinear Optical Rectennas
• Terahertz dynamics of electron-vibron coupling in single molecules with tunable electrostatic potential
• Field enhancement in subnanometer metallic gaps
• Photothermoelectric effects and large photovoltages in plasmonic Au nanowires with nanogaps
• Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces
• Interplay of bias-driven charging and the vibrational Stark effect in molecular junctions
• Coupled-Mode Theory of Field Enhancement in Complex Metal Nanostructures
• Optical wireless link between a nanoscale antenna and a transducing rectenna
• Quantum Plasmonic Nanoantennas
• Enhanced noise at high bias in atomic-scale Au break junctions
• Thermal conductance of metallic atomic-size contacts: Phonon transport and Wiedemann-Franz law
• Tuning light emission crossovers in atomic-scale aluminum plasmonic tunnel junctions
• Light emission and finite frequency shot noise in molecular junctions: from tunneling to contact
• Nanoantenna Enhanced Terahertz Interaction of Biomolecules
• Plasmonic Nano-arrays for Enhanced Photoemission and Photodetection
• Designing plasmonic eigenstates for optical signal transmission in planar channel devices
• Power generation from a radiative thermal source using a large-area infrared rectenna
• Controlling field asymmetry in nanoscale gaps for second harmonic generation
• Field Enhancement in Plasmonic Nanostructures
• Rattling motion of a single atom in a fullerene cage molecule sensed by terahertz spectroscopy
• Optical Rectification and Thermal Currents in Optical Tunneling Gap Antennas
• Remote plasmon--induced heat transfer probed by the electronic transport of a gold nanowire
• The role of titanium in electromigrated tunnel junctions
• Plasmon-assisted photoresponse in Ge-coated bowtie nanojunctions
• Electrical detection of plasmon-induced isomerization in molecule-nanoparticle network devices
• Electroluminescence rectification and high harmonic generation in molecular junctions
• Enhanced Current Density and Asymmetry of Metal-Insulator-Metal Diodes Based on the Self-Assembly of Pt Nanoparticles for Optical Rectennas
• Electrostatics of optical rectification in metallic particles
• Pre-determining the location of electromigrated gaps by nonlinear optical imaging
• Higher harmonics and ac transport from time dependent density functional theory
• Engineering the directionality of hot carrier tunneling in plasmonic tunneling structures
• Quantum Plasmonics: Nonlocal effects in coupled nanowire dimer
• Highly Superlinear Giant Terahertz Photoconductance in GaAs Quantum Point Contacts in the Deep Tunneling Regime
• Plasmons in nanoscale metal junctions: optical rectification and thermometry
• Phononic heat conductance of gold atomic contacts: Coherent versus incoherent transport
• Photovoltages and hot electrons in plasmonic nanogaps
• Consistent analytical solution for the response of a nanoscale circuit to a mode-locked laser
• Ultrafast optically induced tunneling in narrow metallic gaps from the time dependent density functional perspective
• Possibility of coherent electron transport in a nanoscale circuit
• Photonic Contributions to the Apparent Seebeck Coefficient of Plasmonic Metals