Near-field Energy Transfer Research Articles

First-principles investigation of near-field energy transfer between localized quantum emitters in solids

We present a predictive and general approach to investigate near-field energy transfer processes between localized defects in semiconductors, which couples first-principles electronic structure calculations and a nonrelativistic quantum electrodynamics description of photons in the weak-coupling regime. The approach is general and can be readily applied to investigate broad classes of defects in solids. We apply our approach to investigate an exemplar point defect in an oxide, the F center in MgO, and we show that the energy transfer from a magnetic source, e.g., a rare-earth impurity, to the vacancy can lead to spin nonconserving long-lived excitations that are dominant processes in the near field, at distances relevant to the design of photonic devices and ultrahigh dense memories. We also define a descriptor for coherent energy transfer to predict geometrical configurations of emitters to enable long-lived excitations, that are useful to design optical memories in semiconductor and insulators. Published by the American Physical Society 2024

Room-temperature quantum nanoplasmonic coherent perfect absorption

Light-matter superposition states obtained via strong coupling play a decisive role in quantum information processing, but the deleterious effects of material dissipation and environment-induced decoherence inevitably destroy coherent light-matter polaritons over time. Here, we propose the use of coherent perfect absorption under near-field driving to prepare and protect the polaritonic states of a single quantum emitter interacting with a plasmonic nanocavity at room temperature. Our scheme of quantum nanoplasmonic coherent perfect absorption leverages an inherent frequency specificity to selectively initialize the coupled system in a chosen plasmon-emitter dressed state, while the coherent, unidirectional and non-perturbing near-field energy transfer from a proximal plasmonic waveguide can in principle render the dressed state robust against dynamic dissipation under ambient conditions. Our study establishes a previously unexplored paradigm for quantum state preparation and coherence preservation in plasmonic cavity quantum electrodynamics, offering compelling prospects for elevating quantum nanophotonic technologies to ambient temperatures.

The "energy gap law" for mid-infrared nanocrystals.

Colloidal quantum dots are of increasing interest for mid-infrared detection and emission, but device performances will vastly benefit from reducing the non-radiative recombination. Empirically, the photoluminescence quantum yield decreases exponentially toward the mid-infrared, which appears similar to the energy gap law known for molecular fluorescence in the near-infrared. For molecules, the mechanism is electron-vibration coupling and fast internal vibrational relaxation. Here, we explore the possible mechanisms for inorganic quantum dots. The primary mechanism is assigned to an electric dipole near-field energy transfer from the quantum dot electronic transitions to the infrared absorption of surface organic ligands and then to the multiphonon absorption of the quantum dot inorganic core or the surrounding inorganic matrix. In order to obtain luminescent quantum dots in the 3-10μm range, we motivate the importance of using inorganic matrices, which have a higher infrared transparency compared to organic materials. At longer wavelengths, inter-quantum dot energy transfer is noted to be much faster than radiative relaxation, indicating that bright mid-infrared colloidal quantum dot films might then benefit from dilution.

Current-induced near-field radiative energy, linear-momentum, and angular-momentum transfer

Current-induced near-field radiative energy, linear-momentum, and angular-momentum transfer

Efficient 2D to 0D Energy Transfer in HgTe Nanoplatelet-Quantum Dot Heterostructures through High-Speed Exciton Diffusion.

Large area absorbers with localized defect emission are of interest for energy concentration via the antenna effect. Transfer between 2D and 0D quantum-confined structures is advantageous as it affords maximal lateral area antennas with continuously tunable emission. We report the quantum efficiency of energy transfer in in situ grown HgTe nanoplatelet (NPL)/quantum dot (QD) heterostructures to be near unity (>85%), while energy transfer in separately synthesized and well separated solutions of HgTe NPLs to QDs only reaches 47 ± 11% at considerably higher QD concentrations. Using Kinetic Monte Carlo simulations, we estimate an exciton diffusion constant of 1-10 cm2/s in HgTe NPLs, the same magnitude as that of 2D semiconductors. We also simulate in-solution energy transfer between NPLs and QDs, recovering an R-4 dependence consistent with 2D-0D near-field energy transfer even in randomly distributed NPL/QD mixtures. This highlights the advantage of NPLs 2D morphology and the efficiency of NPL/QD heterostructures and mixtures for energy harvesting.

Drift current-induced tunable near-field energy transfer between twist magnetic Weyl semimetals and graphene

Abstract Both the nonreciprocal surface modes in Weyl semimetal (WSM) with a large anomalous Hall effect and the nonreciprocal photon occupation number on a graphene surface induced by the drift current provide a promising way to manipulate the nonreciprocal near-field energy transfer. Interestingly, the interactions between nonreciprocities are highly important for research in (thermal) photonics but remain challenging. In this study, we theoretically investigated the near-field radiative heat flux transfer between a graphene heterostructure supported by a magnetic WSM and a twist-Weyl semimetal (T-WSM). The nonreciprocal surface mode could be changed by the separation space between two Weyl nodes and the twist angle. Notably, we found that in the absence of a temperature difference between two parallel plates, nonequilibrium fluctuations caused by drift currents led to the transfer of near-field radiative heat flux. Furthermore, these nonreciprocal surface modes interacted with the nonreciprocal photon occupation number in graphene to achieve flexible manipulation of the near-field heat flux size and direction. Additionally, graphene adjustable flux in the case of a temperature difference between the two plates was also discussed. Our scheme can provide a reference for near-field heat flux regulation in nonequilibrium systems.

Polariton hybridization phenomena on near-field radiative heat transfer in periodic graphene/α-MoO3 cells

Abstract Coupling of surface plasmon polaritons (SPPs) supported by graphene and hyperbolic phonon polaritons (HPPs) supported by hyperbolic materials (HMs) could effectively promote photon tunneling, and hence the radiative heat transfer. In this work, we investigate the polariton hybridization phenomena on near-field radiative heat transfer (NFRHT) in multilayer heterostructures, which consist of periodic graphene/α-MoO3 cells. Numerical results show that increasing the graphene/α-MoO3 cells can effectively enhance the NFRHT when the vacuum gap is less than 50 nm, but suppresses the enhanced performance with larger gap distance. This depends on the coupling of SPPs and HPPs in the periodic structure, which is analyzed by the energy transmission coefficients distributed in the wavevector space. The influence of the thickness of the α-MoO3 film and the chemical potential of graphene on the NFRHT is investigated. The findings in this work may guide designing high-performance near-field energy transfer and conversion devices based on coupling polaritons.

Significantly boosted photoelectrochemical water splitting performance by plasmonic enhanced Hematite@MOF composite photoelectrodes

Hematite as a catalyst for photoelectrochemical water splitting offers huge potential, due to its high chemical stability, great abundance, and low cost. However, the low water oxidation kinetics and poor charge transportation have hindered progress towards the manufacture of practical water splitting devices. To tackle these problems, a visible light responsive metal-organic framework (MOF) polyhedral zeolitic imidazolate (ZIF-67), and optimised plasmonic Ag nanorods were incorporated into hematite nanostructures to form a three-component heterojunction photoelectrode. The designed photoanode showed dramatically improved light harvesting in the visible range and enhanced charge transport. A mechanistic investigation allowed the deconvolution of the enhanced performance pathways. First, the Hematite@ZIF-67 core-shell p-n junction enables facile charge carrier transfer between ZIF-67 and hematite. In addition, ZIF-67 also provides active sites for water oxidation and boosts surface oxygen evolution reaction (OER) kinetics. Guided by finite-difference time-domain (FDTD) modelling, Ag nanorods with optimised aspect ratio were incorporated between ZIF-67 and hematite. The Ag nanorods facilitate broadband light absorption and surface charge injection, induced by near-field excitation enhancement and plasmonic resonance energy transfer (PRET) pathways. The design and addition of ZIF-67 and Ag nanorods result in superior performance for a hematite-based photoanode for photoelectrochemical (PEC) water oxidation.

Cholesterol-Induced Nanoscale Variations in the Thickness of Phospholipid Membranes.

Graphene-induced energy transfer (GIET) is a recently developed fluorescence-spectroscopic technique that achieves subnanometric optical localization of fluorophores along the optical axis of a microscope. GIET is based on the near-field energy transfer from an optically excited fluorescent molecule to a single sheet of graphene. It has been successfully used for estimating interleaflet distances of single lipid bilayers and for investigating the membrane organization of living mitochondria. In this study, we use GIET to measure the cholesterol-induced subtle changes of membrane thickness at the nanoscale. We quantify membrane thickness variations in supported lipid bilayers (SLBs) as a function of lipid composition and increasing cholesterol content. Our findings demonstrate that GIET is an extremely sensitive tool for investigating nanometric structural changes in biomembranes.

Residual surface charge mediated near-field radiative energy transfer: A topological insulator analog

We study the modifications of near-field radiative energy transfer (NFRET) caused by residual surface charges, which are common in micro- and nano-systems like NEMS/MEMS. The host object with the residual surface charges and the inherent bulk state can be treated as an analog of the real three-dimensional topological insulator, which is inherent of also both surface states and bulk states and is promising to modulate NFRET. Through constructing such a topological insulator analog, we aim to modulate NFRET concerning only common trivial materials. Besides the well-known resonant modes (surface polariton and localized surface polariton) supported by the bulk state, the residual surface charges give rise to an additional temperature-dependent mode providing a new heat flux channel. For low temperatures we find a giant surface-charge-induced enhancement of the NFRET due to a good match between the surface-charge-induced resonance and the Planck window. However, for relative high temperatures where the Fröhlich resonance dominates the heat transfer rather the surface-charge-induced resonance, the residual charges result in a weakening of the NFRET. This work paves way for understanding and modulating the near-field radiative energy transfer for micro- and nano-systems.

Near-Field Retrieval of the Surface Phonon Polariton Dispersion in Free-Standing Silicon Carbide Thin Films

Surface phonon polaritons (SPhPs) are mixed light-matter states originating from strong coupling of photons with lattice vibrations. Thin films of polar dielectrics feature a splitting of the SPhP branch due to the hybridization of the top and bottom interface modes. Recently, enhanced in-plane thermal conductivity and near-field energy transfer have been experimentally demonstrated in free-standing polar films. These effects are determined by the SPhP dispersion in these systems, which, however, is yet to be reported experimentally. In this work, we retrieve the SPhP dispersion in silicon carbide free-standing membranes few hundreds of nanometers thick through near-field spectroscopy. We find several branches in the experimental dispersion, which we rationalize as multiple reflections of tip and edge launched SPhPs, in good agreement with theoretical predictions. Our work paves the way to employ large-area free-standing membranes as a platform for phonon polaritonics, with foreseeable applications in the field of thermal management at the nanoscale.

Moiré-driven reconstitution on electromagnetic energy transfer

The past decade has witnessed an explosion in the field of twistronics concepts, opening the door to numerous extraordinary physical phenomena such as weak ferroelectric charge transfer, superconductivity, topologically protected states, and so on. Here, inspired by the twistronics concepts, we take a moiré three-body system consisting of three metasurfaces supporting highly confined hyperbolic surface plasmons as an example, introducing an analogous concept into the study of near-field electromagnetic energy transfer within three-body system. We demonstrate the possible existence of the moiré transistor effect induced by the twisted hyperbolic repeater in the polariton coupling system (source and drain parallel to each other), where the near-field electromagnetic energy transfer exchanged between the source and the drain can be reversibly switched, amplified, and modulated by action on moiré patterns. Moreover, we point out that for the symmetry-breaking situations (source and drain not parallel to each other), there is also a magic angle in this system and demonstrate that the twisted hyperbolic repeater can act as a moiré compensation effect at this magic angle, mitigating to a certain extent the electromagnetic energy attenuation caused by the malposition between source and drain. Our findings may open new opportunities for the development of near-field thermal energy transport, enabling new perspectives concerning thermal management at the nanoscale, near-field energy conversion, and infrared spectroscopy.

Single-coil Design Approach for Dual-band Near-field Coupled Resonators

With the adoption of single coil approach, printed spiral resonator design strategy for near-field wireless energy transfer is presented. A pair of symmetrical resonators operating at high frequency band specifically 6.78 MHz and 13.56 MHz is designed. Simulated power transfer efficiency (PTE) of over 88% are obtained for both frequencies when coupled spiral resonators separated at a distance of 25 mm is integrated with hybrid compensation network topology. The variance of PTE between both frequencies is about 0.04.

Plasmon-induced near-field and resonance energy transfer enhancement of photodegradation activity by Au wrapped CuS dual-chain

Plasmon-induced near-field and resonance energy transfer enhancement of photodegradation activity by Au wrapped CuS dual-chain

Device, Circuit, and System Design for Enabling Giga-Hertz Large-Area Electronics

Recent progress has substantially increased the operating frequency of large-area electronic (LAE) devices. Their integration into circuits has enabled unprecedented system-level capabilities, towards future wireless applications for the Internet of Things (IoT) and 5G/6G. These exploit large dimensions and flexible form-factors. In this work, we focus on giga-Hertz (GHz) zinc-oxide (ZnO) thin-film transistors (TFTs) as a foundational device for enabling GHz LAE circuits and systems. To further understand their operation and limits in the newly possible frequency regime, we incorporate the effects of temperature and of non-quasi-static (NQS) physics into the device models. We then analyze operation including these effects on a fundamental circuit block, the cross-coupled inductor-capacitor (LC) oscillator. It is used in representative LAE systems, namely a 13.56 MHz radio-frequency identification (RFID) reader array for near-field energy transfer, and a 1 GHz phased array for far-field radiation beam steering. Co-design of devices, circuits, and systems is essential for achieving flexible and meter-scale monolithic integrated LAE wireless systems. For these, understanding temperature limitations and the NQS effect is crucial.

Near-Field Energy Transfer between Graphene and Magneto-Optic Media.

We consider the near-field radiative energy transfer between two separated parallel plates: graphene supported by a substrate and a magneto-optic medium. We first study the scenario in which the two plates have the same temperature. An electric current through the graphene gives rise to nonequilibrium fluctuations and induces energy transfer. Both the magnitude and direction of the energy flux can be controlled by the electric current and an in-plane magnetic field in the magneto-optic medium. This is due to the interplay between the nonreciprocal photon occupation number in the graphene and nonreciprocal surface modes in the magneto-optic plate. Furthermore, we report that a tunable thermoelectric current can be generated in the graphene in the presence of a temperature difference between the two plates.

Imaging Infrared Plasmon Hybridization in Doped Semiconductor Nanocrystal Dimers.

Carrier-doped semiconductor nanocrystals (NCs) offer strong plasmonic responses at frequencies beyond those accessible by conventional plasmonic nanoparticles. Like their noble metal analogues, these emerging materials can harness free space radiation and confine it to the nanoscale but at resonance frequencies that are natively infrared and spectrally tunable by carrier concentration. In this work we combine monochromated STEM-EELS and theoretical modeling to investigate the capability of colloidal indium tin oxide (ITO) NC pairs to form hybridized plasmon modes, providing an additional route to influence the IR plasmon spectrum. These results demonstrate that ITO NCs may have greater coupling strength than expected, emphasizing their potential for near-field enhancement and resonant energy transfer in the IR region.

Mapping Activity-Dependent Quasi-stationary States of Mitochondrial Membranes with Graphene-Induced Energy Transfer Imaging.

Graphene-induced energy transfer (GIET) was recently introduced for sub-nanometric axial localization of fluorescent molecules. GIET relies on near-field energy transfer from an optically excited fluorophore to a single sheet of graphene. Recently, we demonstrated its potential by determining the distance between two leaflets of supported lipid bilayers. Here, we use GIET imaging for mapping quasi-stationary states of the inner and outer mitochondrial membranes before and during adenosine triphosphate (ATP) synthesis. We trigger the ATP synthesis state in vitro by activating mitochondria with precursor molecules. Our results demonstrate that the inner membrane approaches the outer membrane, while the outer membrane does not show any measurable change in average axial position upon activation. The inter-membrane space is reduced by ∼2 nm. This direct experimental observation of the subtle dynamics of mitochondrial membranes and the change in intermembrane distance upon activation is relevant for our understanding of mitochondrial function.

Simulating Ultrasound Piezoelectric Power Transfer in the Near Field and Experimental Validations

Background: Acoustic power transfer is a method for wireless energy transfer to implanted medical devices that permits a greater range of separation between transmitter and receiver than is possible with inductive power transfer. In some cases, short-distance ultrasonic power transfer may be employed; consequently, their operation may be complicated by the near-field aspects of piezoelectric acoustic energy transfer. Methods: A piezoelectric energy transfer system consisting of two lead zirconate titanate (PZT) transducers was analyzed in this work using a combination of experimental measurements and computer simulations. Results: Simulations using the COMSOL Software package showed good agreement with measured output voltage as a function of the distance between and alignment of the transmitter and receiver with water as a medium. We also simulated how operating frequency affects power transfer efficiency at various distances between the transmitter and receiver and found reasonable agreement with experiments. We report model predictions for power transfer efficiency as a function of the thickness and diameter of the transmitter and receiver. Conclusion: The results show that with proper choice of parameters, piezoelectric systems can provide high power transfer efficiency in the near-field region.

Design of Single-Layer Polarization-Dependent Transmissive and Reflective Focusing Metasurface

A polarization-dependent transmissive and reflective phase-gradient metasurface (PGMS) is investigated and experimentally verified in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ku$ </tex-math></inline-formula> -band. The PGMS is based on a single-layer substrate-integrated element, which consists of a cross-shaped dielectric unit and a couple of metallic strips/patches that are printed on the dielectric unit. Taking advantage of both the dielectric and the metallic components, the proposed element can transmit or reflect the linearly polarized (LP) incident wave depending on its polarization. Moreover, the phase of the transmitted or reflected wave can be independently controlled by different phase-control parameters. As a result, two independent foci can be obtained on the transmission and reflection sides of the PGMS for two orthogonal LP waves. For demonstration, a prototype of the PGMS is fabricated and tested. Both the transmissive and reflective foci are observed at the target positions. Also, the PGMS is shown to be able to manipulate the wavefronts independently on its two sides by adjusting the phase distributions. These features make the proposed PGMS a great choice for use in polarization identification, near-field energy transfer, or far-field wireless communication.