Search results for "plasmonics"
showing 10 items of 41 documents
Tunable Optical Antennas Using Vanadium Dioxide Metal-Insulator Phase Transitions
2019
Here, we investigate the possibility of exploiting the insulator-to-metal transition in vanadium dioxide (VO2) to tune and optically control the resonances of dipole nanoantennas in the visible near-infrared region. We compare the results obtained in the case of antennas completely made by VO2 with those of previous works and highlight the key role of the substrate to perform dynamical tuning. We also present a highly efficient configuration composed of dipole gold antenna loaded with VO2 and give some general guidelines to optimally exploit phase transitions to tune nanodevices.
Plasmonic versus catalytic effect of gold nanoparticles on mesoporous TiO2 electrodes for water splitting
2014
a b s t r a c t Solar water splitting with metal oxide semiconductors constitutes a promising approach to the conversion of solar energy into chemical energy stored in the atomic bonds of hydrogen molecules. In the present study, we evaluate the effect of the presence of Au nanoparticles on the photoelectrochemical behaviour of mesoporous TiO2 to photo-oxidize water. We observe that the presence of Au nanoparticles leads to enhanced photocurrents for water oxidation and we explore the origin of this enhancement by optical and electrochemical characterization techniques. Our results indicate that although the Au nanoparticles are responsible for a localized surface plasmonic resonance effect…
Electrical control of the nonlinear properties of plasmonic nanostructures
2020
This work brings nano-electronics and nano-photonics technologies together to create an electron- plasmon device whose linear and nonlinear optical properties are electrically controlled. Here, we present the first demonstration of nonlinear photoluminescence modulation by electrical means in an uncluttered configuration. To this purpose, plasmonic nanoantennas are interfaced with elec- trical connections inducing localized regions of electron accumulation and depletion and therefore affecting the optical response. Additionally, a complete analysis of the nonlinear photoluminescence in plasmonic nanowires is carried out. The delocalization and transport of nonlinearities provided by such st…
Nonlinear photon-assisted tunneling transport in optical gap antennas.
2014
International audience; We introduce strongly coupled optical gap antennas to interface optical radiation with current-carrying electrons at the nanoscale. The transducer relies on the nonlinear optical and electrical properties of an optical gap antenna operating in the tunneling regime. We discuss the underlying physical mechanisms controlling the conversion involving d-band electrons and demonstrate that a simple two-wire optical antenna can provide advanced optoelectronic functionalities beyond tailoring the electromagnetic response of a single emitter. Interfacing an electronic command layer with a nanoscale optical device may thus be facilitated by the optical rectennas discussed here.
Field Dependence of the Electron Spin Relaxation in Quantum Dots
2005
Interaction of the electron spin with local elastic twists due to transverse phonons has been studied. Universal dependence of the spin relaxation rate on the strength and direction of the magnetic field has been obtained in terms of the electron gyromagnetic tensor and macroscopic elastic constants of the solid. The theory contains no unknown parameters and it can be easily tested in experiment. At high magnetic field it provides parameter-free lower bound on the electron spin relaxation in quantum dots.
Theory of Kondo suppression of spin polarization in nonlocal spin valves
2016
We theoretically analyze contributions from the Kondo effect to the spin polarization and spin diffusion length in all-metal nonlocal spin valves. Interdiffusion of ferromagnetic atoms into the normal metal layer creates a region in which Kondo physics plays a significant role, giving discrepancies between experiment and existing theory. We start from a simple model and construct a modified spin drift-diffusion equation which clearly demonstrates how the Kondo physics not only suppresses the electrical conductivity but even more strongly reduces the spin diffusion length. We also present an explicit expression for the suppression of spin polarization due to Kondo physics in an illustrative …
Direct observation of spin wave focusing by a Fresnel lens
2020
Spin waves are discussed as promising information carrier for beyond complementary metal-oxide semiconductor data processing. One major challenge is guiding and steering of spin waves in a uniform film. Here, we explore the use of diffractive optics for these tasks by nanoscale real-space imaging using x-ray microscopy and careful analysis with micromagnetic simulations. We discuss the properties of the focused caustic beams that are generated by a Fresnel-type zone plate and demonstrate control and steering of the focal spot. Thus, we present a steerable and intense nanometer-sized spin-wave source. Potentially, this could be used to selectively illuminate magnonic devices like nano-oscill…
Quantum theory of light in linear media : applications to quantum optics and quantum plasmonics
2020
We develop a method of quantization of the electromagnetic field interacting with passive media on one hand, and active (plasmonic) media on the other hand. This method relies on the construction of a Hamiltonian structure compatible with the Maxwell equations, and then on a principle of correspondence and the definition of a Fock space of quantum states. We use the results of the quantum theory to study the propagation of photons in dielectric environments and the emission of single plasmons.
Theoretical Evaluation of [V IV (α-C 3 S 5 ) 3 ] 2– as Nuclear-Spin-Sensitive Single-Molecule Spin Transistor
2017
In a straightforward application of molecular nanospintronics to quantum computing, single-molecule spin transistors can be used to measure nuclear spin qubits. Conductance jumps accompany electronic spin flips at the so-called anticrossings between energy levels, which take place only at specific magnetic fields determined by the nuclear spin state. To date, the only molecular hardware employed for this technique has been the terbium(III) bis(phthalocyaninato) complex. Here we explore theoretically whether a similar behavior is expected for a highly stable molecular spin qubit, the vanadium tris-dithiolate complex [VIV(α-C3S5)3]2–. We consider such a molecule between two gold electrodes an…
Quantum Nanoplasmonic : from dressed atom picture to superradiance
2019
Controlling quantum emitters (atoms, molecules, quantum dots, etc.), light, and its interactions is a key issue for implementing devices for information optical processing at the quantum level. For example, controlling dynamics of emitters coupled to a high-Q cavity can be achieved through cavity quantum electrodynamics (cQED). Plasmonic structures hybrid system are of growing interest in the quantum control at the nanoscale because of their capability to confine light beyond the diffraction limit. However, its application appears notoriously limited in practical situations due to the intrinsic presence of numerous and lossy modes, which complicates the description and the interpretation of…