INC Summer School 2018: Schedule & Abstracts

We present a theoretical study of fluorescence of dye molecules embedded within metallic (Ag or Au) multilayered nanocapsules. The photon emission is triggered by the $\beta^-$ radiactive decay of an isotope attached to the capsule external boundary. We combine numerical and quasi-analytical calculations showing that by designing the metallic structure properly enhancements of several orders of magnitude can be obtained in the fluorescence power per radioactive decay.

Figure: Left: Schematic representation of our system. Right: Field enhancement at the center of the multilayered system for gold computed using Mie theory for different number of layers.

Achieving thermal control of molecular systems is a topic of current interest for a wide variety of applications. In this study, we explore whether localized surface plasmon polariton modes can transfer heat between molecules placed in the hot spot of a nanoplasmonic cavity through optomechanical interaction with the molecular vibrations. We demonstrate that external driving of the plasmon resonance indeed can lead to heat transfer between molecules. The plasmonic resonance induces an effective molecule-molecule interaction corresponding to a new heat transfer mechanism. This allows to actively control the rate of heat flow through the pumping and detuning frequency of the driving laser.

In recent years, chemically synthesized monocrystalline gold flakes have drawn considerable attention within the plasmonic community. Well-defined crystal structure as well as superior optical properties of this material are primarily important for applications, but also are interesting for the basic research.

In this work we report on strongly dissimilar scattering from two types of edges in hexagonal quasi-monocrystalline gold flakes with thicknesses around 1 micron. Experimentally it manifests in dark field microscopy, appearing as distinct colors of the adjacent edges that alter around the flake. Morphologically, the two types of edges differ in the orientation of asymmetrically tapered facets, which is a direct consequence of the three-fold symmetry around the [111]-axis and the intrinsic chirality of a face-centred cubic lattice.

In order to explain the apparent difference in scattering, we have developed a numerical model and filtering method which allows to simulate the experimental conditions. Based on the numerical results we propose an analytical model and identify the main physical mechanism of the observed phenomenon. In short, that is the interference between a direct, quasi-specular scattering and an indirect scattering process involving an intermediate surface-plasmon state.

We propose that this effect can be used to estimate flake thickness, crystal morphology, surface contamination and (assuming those parameters are fixed by other means) could provide a sensitive probe to the plasmonic properties of monocrystalline metals.

Figure: (a) SEM image of the Au monocrystalline flake (75° tilted view, scale bar: 10 µm) (b) and (c) close-up high resolution SEM image of the two corners of the flake (75° tilted view, scale bar: 500 nm); Artificial coloration is used to highlight different crystallographic planes of the facets: {111} (light yellow) and {100} (dark yellow); (d) bright-field optical image of the flake and (e-h) dark-field optical images of the flake captured with 4 different NA’s (indicated in the images) (scale bars: 10 µm)

In the last decade experiments at the interface between chemistry, material science and quantum optics have uncovered situations in which the strong interplay between the quantized electromagnetic field and the matter degrees of freedom lead to interesting physical effects and novel states of matter [1,2]. The theoretical description of such situations require a precise description of the involved (correlated) many-electron system, the full quantum mechanical treatment of the electromagnetic field, and validity in the strong coupling regime. It seems natural to extend electronic many-body theories to such coupled electron-photon systems, and for example recently, quantum-electrodynamical density functional theory (QED-DFT) was proposed [3]. However, the strong coupling regime is difficult to capture in QED-DFT, and learning from electronic structure theory, a promising candidate that describes strongly-correlated electrons well in many situations, is reduced density matrix functional theory (RDMFT). RDMFT approximates the 2-body reduced density matrix (2RDM), that carries all important information about electronic (Coulomb) interaction, by a functional of the 1-body reduced density matrix (1RDM). Instead in the present case, the respective RDM that carries all information about the electron-photon interaction, has to be characterized and approximated. In my poster I want to briefly explain the problems of transfering RDMFT from the purely electronic to the coupled electron-photon case. Then I will show an alternative approach that circumvents these problems by embedding the coupled system in a higher dimensional space. This allows for introducing new (quasi-) particles that are fermions and that’s energy can be expressed completely by the 2RDM of this higher dimensional system. Thus any standard electronic many-body technique can be applied to approximate the 2RDM and I will show results for Hartree-Fock Theory and RDMFT. This is to my knowledge the first RDMFT for coupled electron-boson systems.

Monolayer transition metal dichalcogenides (2D-TMDs) with the chemical formula MX₂ (M = Mo, W and X = Se, S) are direct bandgap semiconductors that exhibit strong excitonic resonances resulting in large absorption and photoluminescence. Therefore, they offer an excellent platform for low-dimensional optoelectronic applications. However, typical optoelectronic devices, such as lasers and light-emitting diodes, must meet requirements that include high quantum yield (QY), large spontaneous emission and directional emission. In contrast, 2D-TMDs exhibit long emission lifetimes (~ns) and poor quantum yields (~1-10%). The relaxation pathways of these materials are dominated by nonradiative processes, namely defect-mediated recombination and exciton-exciton annihilation. While defect-mediated recombination has been observed to disappear after treatment with organic superacids, exciton-exciton annihilation remains a problem at typical excitation powers used in optoelectronic devices. One way to improve the emission properties consists in modifying the photonic environment by coupling 2D-TMDs to optical nanocavities. In the weak-coupling regime, the increased local density of states (LDOS) results in emission rate enhancements (the Purcell effect). In this contribution, we investigate with FDTD simulations the QY enhancements in 2D-TMDs achievable with array of nanoantennas. Owing to the coherent scattering, arrays offer higher directionality than single antennas. In addition, diffractive coupling of nanoantennas by Rayleigh anomalies results in extended optical modes known as surface lattice resonances (SLRs). Here we use these SLRs to obtain an average QY enhancement over large areas. Finally, we have considered both plasmonic and all-dielectric arrays. While plasmonic antennas offer small mode volumes, high-index dielectric nanoparticles present smaller absorption. Combining high-directionality with a moderate QY enhancement opens the possibility of low-dimensional and efficient light-emitting devices.

The exponentially increasing bandwidth requirement for the internet generation and multimedia applications is pushing optical communications ever closer to the end user. In the last 20 years, the development of new optical technologies for device miniaturization has accelerated significantly. Comparing with conventional optical devices, the PC based optical devices have attracted great interest due to their compactness, speed of operation, long life and suitability for PICs. Typically, PCs are composed of periodic dielectric and/or metallo-dielectric nanostructures that have alternate low and high relative permittivity materials to affect the propagation of electromagnetic (e.m) waves inside the periodic structure in certain frequency ranges. As a result of this periodicity the transmission of light is absolutely zero over certain frequency ranges which are called as Photonic Bandgap (PBG). By introducing the defects in these structures, the periodicity and thus the completeness of the PBG are broken. Recent years, many Two Dimensional (2D) PC based optical devices are designed and analyzed to name a few, optical filters, power splitters, multiplexers, demultiplexers, polarization beam splitters, triplexers, switches, directional couplers etc. Conventional CDFs, such as Bragg grating filters, Fabry-Perot filters, acoustic optic filters, thin film filters, arrayed waveguide grating filters and micro-ring resonator filters are in the scale of centimeters, which may not be suitable for PICs. Among these, the micro-ring resonator based CDF is an attractive candidate for filtering applications and contribute better performance because of its circular resonating mode. However, when the radius of the ring resonator decreases below 5 µm, it exponentially increases the propagation and bending losses. These affect the coupling and dropping efficiencies, passband width in turn Q factor of the filter. Photonic Crystal (PC) based Channel Drop Filter (CDF) is one of the right candidates to overcome this issue as it is not allowing these losses to increase exponentially.

When matter strongly couples to confined light modes, new hybrid light-matter states so-called polaritons can form. Within this context, polaritonic chemistry aims to manipulate molecular structure under such strong coupling regime. While the general theory of polaritonic chemistry due to electronic strong coupling is well established [1], theoretical studies describing the modification of ground-state chemistry through strong coupling between molecular vibrations and microcavity modes [2,3] are still missing. In this communication we will show our recent efforts in this direction. We use the cavity Born-Oppenheimer [4] description of the coupled light-matter system as a starting point and show that the effective light-matter potential energy surface governing ground-state reactions depends sensitively on the molecular dipole moment. Based on full electronic-structure calculations for complex molecules, we identify several reactions that could be promising candidates for control through vibrational strong coupling.

In the last few years a number of papers investigated the possibility to exploit light-matter coupling to modify chemical or mechanical properties of molecules strongly coupled to a cavity photonic field [1,2]. Those seminal works demonstrated that only very specific, collective observables are accessible in this way. Single-molecule properties are instead usually not accessible, because the relevant energy scale is in this case not the collective, superradiant vacuum Rabi frequency, but the tiny single-molecule one. In a recent work [3] we showed that this limitation can be overcome in highly excited systems. In particular we studied a collection of asymmetric two-dimensional, freely rotating dipoles coupled to a cavity field, sketched in the left panel of Fig. 1. We demonstrated that the thermodynamics of the system is regulated by the single parameter Λ, which is the inverse temperature renormalized by the vacuum Rabi frequency and the excitation density. At low Λ (high temperature or low excitation density) the molecules are isotropically distributed, while at high Λ (low temperature or high excitation density) all the molecules are aligned with the cavity field. In the right panel of Fig. 1 we can see that, as Λ is modified, the system undergoes a second order phase transition from the disordered to the ordered phase, which can be detected as a change in the frequency of polaritonic luminescence. Such a phase transition should be observable in organic, liquid phase microcavities [4].

Figure: (left) Schematic representation of the system under investigation: a set of asymmetric, freely rotating molecules coupled to the field of a photonic cavity. (right) Frequency of the polaritonic emission as a function of the normalized inverse temperature Λ, clearly showing a second order phase transition.

By means of Transformation Optics [1], we investigate theoretically the interaction between particle-on-a-mirror localized plasmons and two types of nano-emitters: dipolar and quadrupolar ones. Our 2D conformal mapping technique allows for the exact description of the Purcell effect in this geometry within the quasi-static limit. The analytical character of our solutions provides deep insights into the dependence of the emitter-plasmon coupling on the system parameters. Our results indicate that the large near-field gradients [2] taking place at the nanogap yield quadrupolar emission rate enhancements (into the plasmon field) orders of magnitude larger than those experienced by dipolar emitters. Further analysis delves into Near Field Dynamics and Far Field Signatures, providing a platform to study the emergence of different regimes of Strong Coupling among the emitter levels and the plasmonic modes.

Figure: Purcell Factor versus frequency and normalized gap size for a nanowire on top of a flat metal surface (gap center and Drude fitting for Ag permittivity). a) Dipolar emitter normal to the flat surface. b) Purcell Ratio between dipolar and quadrupolar sources in a) and c) for various values of the normalized gap size. c) Quadrupolar emitter with an antidiagonal quadrupole tensor form. Insets: Purcell Factors for different dipole and quadrupole orientations.

Light driven processing of amorphous materials is widely studied in the field of nano-manufacturing, laser information storage, optoelectronics and material science. Recently it was found that resonating dielectric nanoparticles can experience a large temperature, even with low exciting power [1,2]. However contradictory results are present in literature about the topic []. When considering the laser processing of nanostructures, the resonant driven melting or crystallization has never been studied before. In this work we first elucidate the features affecting heating in Silicon nanostructures, the role of resonance and of structural features. Afterwards we study the light driven processes of crystallization and melting as a function of different light-coupling condition. Considering the change of thermal and optical proprieties during the process, we found that a wide variety of unexplored phenomena take place. Light coupling, drive the crystallization/melting kinetics and even have a crucial role in the the spatial evolution of the process. Deep subwavelength domains of crystalline material, can be embedded in an amorphous nanoantenna matrix. While the process take place, optical proprieties has been monitored, showing largely enhanced optical absorbance and scattering respect to the fully amorphous or fully crystalline counterparts. When melting temperature is reached, the resonating particles, show a self-limiting melting, due to the decoupling of the antenna from the radiation. The result is a partially melted system. If the unmelted portion of a-Si undergoes the crystallization, the melted region re-solidify in a crystalline way. Counterwise, melting of a non-resonating system, can bring the particle in resonance, resulting in a self-sustaining explosive melting.

We investigate the dipole-dipole interactions between two circularly-polarized quantum emitters held above a metallic surface hosting plasmons. Depending on the positions of the emitters, we find that the nature of the coupling evolves from non-chiral to chiral, thus realizing non-reciprocity at the subwavelength scale in a tunable manner. We explore the physically rich phase space of the effective coupling, which is a combination of coherent and dissipative components, and find novel and exotic features in both the one and two-photon spectra of the system. In particular, we highlight that the quasichiral regime, that between the reciprocal and chiral limits, is interesting by itself, and report hitherto unknown spectral peaks and photon correlations.

In recent years, hybrid matter-light systems such as microcavity polaritons have been proven ideal for the study of spontaneous pattern formation. Resulting from the strong coupling between cavity photons and quantum well excitons, microcavity polaritons share the properties of both components and, thus, display unique properties: among those, optical and electrical injection, a high degree of tunability and control, easy detection and direct read-out. There has been an increasing interest in recent years on pattern formation in microcavity structures. Optical parametric oscillation is a paradigm of polariton spontaneous pattern formation. More recently, same energy instabilities have been realised in triple and double cavities, as well as by blue-shifting the pump above the polariton dispersion in one dimensional cavities. Interestingly, there is an analogy between optical patterns and Turing patterns, where spontaneous self-organised repetitive spatial configurations emerge out of a homogeneous distribution. In this contribution [1], we consider a polariton microcavity resonantly driven by two external lasers which simultaneously pump both lower and upper polariton branches at normal incidence. In this setup, we study the occurrence of instabilities of the pump only solutions towards the spontaneous formation of patterns. Their appearance is a consequence of the spontaneous symmetry breaking of translational and rotational invariance due to interaction induced parametric scattering. We observe the evolution between diverse patterns which can be classified as single-pump, where parametric scattering occurs at the same energy as one of the pumps, and as two-pump, where scattering occurs at a different energy. For two-pump instabilities, stripe and chequerboard patterns become the dominant steady-state solutions because cubic parametric scattering processes are forbidden. This contrasts with the single-pump case, where hexagonal patterns are the most common arrangements. We study the possibility of controlling the evolution between different patterns. Our results are obtained within a linear stability analysis and are confirmed by finite size full numerical calculations.

Figure: Photon emission from a specific stable chequerboard configuration. Top panels: Photonic spectra. Bottom panels: Photon density profiles in real (right) and reciprocal (left) spaces, filtered at the energy of the signal states $\omega_s = (\omega_{p1} + \omega_{p2})/2$.

The strong coupling regime, i.e. the coherent exchange of energy between matter and radiation in optical cavities, was initially modelled by Jaynes and Cummings [1]. Recent achievements of strong light-matter couplings [2] have unravelled a manyfold of exotic applications, ranging from enhanced optical response to quantum information, sensing and polaritonic chemistry [3]. The latter aims to study how the electronic states of molecules are modified by the coherent coupling of molecules with an electromagnetic field. The system potential energy surfaces are then described by the definition of hybrid light-matter states: the polaritons. The modulation of Polaritonic Potential Energy Surfaces (PoPESs) through light-matter coupling brings, in principle, the possibility to control the quantum yields of photochemical reactions, recently shown on model molecules [4]. Non-adiabatic dynamics (NAD) methods have been developed to simulate photochemical reactions extensively, providing a good starting point for polaritonic chemistry. In our work, we make a step toward the realistic description of azobenzene photoisomerization reaction on PoPESs. To this aim, we exploit a modified version of the Direct Trajectory Surface Hopping (DTSH)[5] method devised by Granucci, Persico and coworkers. Such method conjugates the low computational burden of a semiempirical description with a good level of accuracy provided by high-quality parametrization of the electronic hamiltonian. The results in the computation of PoPESs with an extended Jaynes-Cummings model and some examples of photoisomerization on polaritonic states are presented.

Controlling chemical processes with light has long been a topic of great interest in many different fields of science. One of the most promising directions towards this goal is employing the light-matter strong coupling phenomenon with organic molecules. This interaction regime is achieved when the coherent energy exchange between a confined electromagnetic field mode and material excitations (excitons) becomes faster than the decay and decoherence of either constituent. The resulting excitations of the system, the so-called polaritons, have a hybrid behavior, presenting both light and matter characteristics. Under strong coupling, the molecular “landscape”, i.e., the potential energy surfaces (PES) that describe nuclear motion in a given electronic state, are modified by the coupling of the electronic transitions to the light mode. This opens the possibility to modify chemical reactions under strong coupling, as first experimentally demonstrated in 2012 [1]. Since then, many theoretical and experimental efforts have been devoted to this new field of research, known as polaritonic chemistry [2]. We will discuss the possibilities of polaritonic chemistry, and demonstrate that it can be used to influence chemical reactions and organic molecule properties in different manners, such as complete suppression of photochemical reactions, or triggering of excited-state reactions in many molecules through single-photon absorption. We additionally present a quantum mechanical formalism that allows to study the influence of strong coupling on ground state reactivity. We will study which molecular properties this approach is sensitive to and discuss candidate molecules and reactions that could be modified through vibrational strong coupling.

Open-access tunable microcavities offer the possibility to spatially and spectrally match any nanoscale emitter to any confined cavity mode in-situ. State-of-the-art tunable cavity systems have demonstrated mode volumes on the order of $\lambda^3$, and quality factors $Q\sim 10^5$. Herein, we present preliminary experimental results we have obtained with open-access tunable microcavities hosting different emitters at room-temperature, such as organic molecules and perovskites. In white light transmission spectra as a function of the cavity length, we have observed the avoided resonance crossing characterizing the strong light-matter coupling regime. We have also observed a strong cavity-enhanced emission from perovskite quantum cubes. We are planning to investigate nonlinear phenomena emerging form polariton-polariton interactions, and to extend the single nonlinear microcavity to microcavity lattices. We will also present our current plans to perform similar experiments in a closed-cycle cryostat.

Silicon nanocrystals (Si NCs) embedded in silicon dioxide (SiO₂) or oxinitrides (SiO_xN_y) have been shown to provide high photoluminescence (PL) external quantum yield (EQY) of up to 27% which is size-tunable in the spectral region from orange to near infrared (NIR), i.e. about 650 – 1100 nm [1]. Such quality can be potentially exploited to provide photon conversion in lighting and photovoltaic devices. We provide comprehensive study of both external and internal luminescence quantum yield (IQY) of Si NC/SiO₂ multilayers for different temperatures (4 – 300 K). EQY is defined as the ratio of total number of emitted to absorbed photons for the whole ensemble, while IQY concerns only the luminescing (bright) subensemble of NCs and is equal to the ratio of radiative and total decay rates. Some Si NCs in ensemble are “dark”, i.e. they absorb but not emit photons due to the presence of non-radiative recombination centres (defects) or due to transient switching-off (blinking). EQY is measured using an integrating sphere [2] while IQY is derived using variation of local density of optical states (LDOS) which affects radiative but not non-radiative lifetime, so enabling to decouple these two components. We study IQY using special wedge samples with variable distance between Si NCs and a high-n substrate resulting in position-depending Purcell factor (which directly effects radiative lifetimes) [3]. While the near-infrared emission (close to the bulk Si bandgap) is almost ideal (IQY > 80 %), both IQY and population of bright NCs decreases toward shorter wavelengths causing vanishing PL below 600 nm.

Surface phonon polaritons (SPhPs) are formed by hybridisation of photons with the coherent oscillations of a polar dielectric crystal. Like plasmons these modes allow for confinement of light on the nanoscale. Unlike plasmons, SPhPS typically have narrow linewidths and corresponding long lifetimes [1]. SPhPs are supported in the mid-infrared spectral region, specifically in the Reststrahlen region between the supporting polar dielectric’s transverse and longitudinal optical phonon frequencies. Their large intrinsic nonlinearities [2,3] and ease of fabrication make SPhP systems an excellent platform for mid-infrared nonlinear optics. Although the phonon branches of a polar dielectric crystal are dispersive the optical properties of the SPhP systems studied thusfar are dependent solely on the zone-centre phonon frequencies of the lattice. This is because the lengthscale of a typical SPhP nanoresonator is 100nm, many orders of magnitude larger than the supporting polar dielectric’s lattice constant. This talk will discuss a system where this zone-centre treatment of the lattice fails. Exploiting the polymorphism of silicon carbide, whose polytypes unit cells are identical in two dimensions but extended to varying degree in the third, it is possible to fold the dispersive longitudinal optical phonon of the lattice back to zone-centre. We will discuss the implications of this folding for the optical response of SPhP nanoresonators, demonstrating that their optical modes can be hybridised with this folded longitudinal phonon to create a mixed longitudinal-transverse mode. In addition we will discuss the possibility of exploiting these hybridised modes to create electrically pumped SPhP devices.

Super-resolution microscopy is a form of optical microscopy that allows images to be taken with a higher resolution than the diffraction limit^1,2. We use super-resolution microscopy 1) to study site-selective catalysis on individual Au nanostructures and 2) to map the coupling between fluorescent molecules and metal nanoparticle arrays. First, we study the effect of the decay of localized surface plasmon resonances on the catalytic properties of metal nanoparticles³. As a test reaction we use the nanoparticle-catalyzed reduction of the weakly fluorescent molecule resazurin to the strongly fluorescent molecule resorufin^4,5. By using catalysts with a plasmon resonance spectrally separated from the absorption and emission of the reaction products and by controlling the polarization of the incident fields, we can study the different contributions of plasmonic hot electrons, plasmonic heating, and coupling between the reactions products and the catalysts. Second, we investigate the coupling between fluorescent molecules and a periodic array of metallic nanoparticles. Due to their ability to support surface lattice resonances⁶, these arrays can enhance the emissive properties of fluorescent molecules across the whole unit cell of the array, instead of just in the vicinity of the nanostructure⁷. However, accurately mapping this enhancement is challenging, as the pitch of the array is typically of the order of the diffraction limit. Using our super-resolution microscope, we are able to map the emission of fluorescent molecules dispersed above a nanoparticle array with a spatial accuracy of ~20 nm, allowing sub-unit cell properties to be visualized. As the influence of the particle array on the emission depends strongly on the position of the fluorescent molecule in the unit cell, mapping the emission enhancement as a function of position in the unit cell is instrumental for the optimization of these devices.

Micromotion is a quickly evolving research field. To enable motion at the microscale, a swimmer requires constant energy input. Because of the high Reynolds number at such conditions, a discontinuation of energy input would immidiately cause a micromotor to stop. Among different motion mechanisms for micromotors such as catalytic reactions, magnetic fields and ultrasound, light-driven micromotors show some advantageous properties. Light as an energy source can easily be applied remotely and is also renewable. When excited by light of a certain wavelength, a photocatalytic material in the micromotor catalyses the degradation of a certain fuel and is accelerated by the gas formation of that reaction. Until a few years ago, light-driven micromotors could only move in highly oxidizing fuels like H2O2 due to a lack of sufficient photocatalysis materials that enable other fuels. This prevented micromotors to develop towards application-oriented research. Recently, materials like BiVO4 showed great potential as such photocatalytic materials and micromotors that use H2O as a fuel, activated by UV light, could be demonstrated. Despite those advances, light-driven micromotors still lack a general understanding of their motion principles and collective behaviour on the one side and photoactive materials that can be activated by visible light on the other side. Only by expanding the pool of materials, light-driven micromotors will become possible alternatives for sensing, environmental remediation and bioapplications. To achieve those goals, this poster presents new photoactive materials for micromotors.

Aiming for the improved performance of a micro ring resonator biosensor platform we will analyse the influence of noise on the limit of detection and investigate the effect of the field overlap with the analyte. As the physical limit of detection is primarily determined by the noise floor of the sensors and the sensitivity of the sensor. We will show that an increased field overlap increases the sensitivity of our system while simultaneously leading to a higher noise floor thereby not improving the actual limit of detection. Therefore In order to reduce the noise influence we consider the improvement that can be obtained by a referenced sensor configuration.

The anisotropic optical response of Au/Co magnetoplasmonic nanodisks is studied in the mean field approximation. Lorentz like oscillators are considered to model the real and imaginary components of the dielectric tensor of the system showing good agreement with spectral ellipsometry measurements. The analysis allows for the detection of two in-plane plasmonic modes, as well as a normal to the disks mode. A further analysis of the sensitivity of the optical properties to the dielectric environment of the nanodisks shows al well-behaved evolution of the in-plane modes which undergo a red-shift, while the out-of-plan mode suffers an unexpected blue-shift.

Hole-mask colloidal lithography is a low cost nanofabrication technique, which involves self-organization of colloidal particles on a thin PMMA layer to perform a sacrificial mask, from which nanostructures are created by physical vapor deposition over large areas [1]. However, it has some limitations in the range of patterns that can be fabricated due to its formation principle, where the inclination of sample is necessary [2]. In order to extend the range of possible patterns that can be fabricated and their potential applicability we have created an atomic version of a pinhole camera using hole-mask colloidal lithography. Previously nanolithography based on an atom pinhole camera has been demonstrated [3], but nanoscale membranes manufactured by the method of ion beam milling are required, restricting the fabrication of nanostructures to a small area. In this work, we have created colloidal hole-masks based on self-assembly with thick PMMA layers to avoid the use of membranes allowing nanostructures fabrication over large areas. Traditional hole-mask colloidal lithography typically works with thin PMMA layers around 200 nanometers in thickness. In this work, we use PMMA layers of several micrometers thickness, we have modified etching conditions increasing the power to create a thick hole-mask. Initial experiments using 2-micrometer PMMA layer showed a partial projection of a gammadion design with an approximate size reduction of 4800. Different parts of the gammadion were projected in different parts of the sample due to the limited surface area at the bottom of the etched hole and the small angle of view. We have chosen this design due to its rotational symmetry for sensitivity enhancement in sensing applications [4, 5]. By modifying hole-mask characteristics and adding an intersection mask, we have developed a novel fabrication route to achieve nanostructures for a broad range of future applications.

In this work, we present a fine control over the coupling strength of light–matter hybrid states by controlling the orientation of a nematic liquid crystal. The microcavity was made from ITO-Gold electrode/mirrors on IR-transparent CaF₂ substrates (Fig. 1a). Through an external voltage, the liquid crystal is seamlessly switched between two orthogonal directions. The C – N vibration on the liquid crystal molecule is coupled to a cavity mode, and FT-IR is used to probe the formed vibro–polaritonic states. Using these features, we demonstrate electrical switching and increased Rabi splitting through transition dipole moment alignment compared to an isotropic phase. Moreover, the scalar product used in the modelisation of light–matter interaction is verified [1].

Figure: Left: Photography of a microcavity. Right: Rabi-splitting $\hbar\Omega_{R}$ as a function of applied voltage over the cavity monitoring with the polarizer parallel (orange) or perpendicular (grey) to the alignment layer.

In the view of the recent work, we have investigated the development of the electronic, magnetic, and optical properties of ferromagnetic materials of iron (Fe) and cobalt (Co) nanowires. All calculations are systematically investigated using the first principles approach, with ultrasoft and spin–orbit coupling potentials within density functional theory under generalized gradient approximation as from linear chains (LCs) (1-D structure) to zigzag (ZZ) structure to 2×2 NWs. The magnetic properties of Fe and Co (spin and orbital magnetic moments, magnetocrystalline anisotropy energy) in multifarious geometries are calculated by using a first principles calculation in atomic orbital basis set including spin polarization and the effect of SOC. Here we have also compared the axial anisotropy, magnetic moment and cohesive energy for the different diameter of all three structures and also accumulation transverse of charge density. The thermodynamical properties are calculated using BoltzTrap code in quasi harmonic approximation (QHA). This work looks into the properties of nanowires and the multiple ways in which they have been exploited for energy generation, from photovoltaics to piezoelectric generators.

Spatial structured light fields can carry an orbital angular momentum encoded in their phase, in addition to the spin angular momentum connected with the circular polarization. The additional degree of freedom of orbital angular momentum can be exploited to carry information, what makes orbital angular momentum light attractive for future communication technologies. Because of the helical wavefront these light beams are also called twisted light. To measure the value of orbital angular momentum of a twisted light beam we here propose an approach using plasmonic nanostructures to convert the phase information into spectral information. We analyze the resonance modes of nanoantennas excited by orbital angular momentum light numerically using the boundary element method and analytically using a line antenna model. For rotation-symmetrical nanorod antennas we show that dependent on the combination of the value of orbital angular momentum, the handedness of circular polarization and the discrete rotation symmetry of the antenna the scattering cross-section exhibits different resonance modes which can be classified into bright and dark modes [1]. Using these resonance modes we propose a scheme to read out the OAM of a twisted light beam.

The use of cavities to shape the electromagnetic field has been a successful tool across many experimental platforms and has enabled the access to new regimes of light-matter interaction. In recent years X-ray nanomaterials doped with Mössbauer nuclei have been added as yet another platform of cavity QED and have shown their potential with the observation of a number of quantum optical phenomena in this system [1,2]. With a new platform come new theoretical challenges. Due to material limitations X-ray cavities do not have the quality factors that can be achieved for example in microwave cavities. This inhibits progress in several ways, since strong coupling and non-linearities become hard to achieve. However it allows to explore a new cavity QED regime, where multiple broad cavity resonances participate in the dynamics, known as the “overlapping mode regime”. On the other hand the Mössbauer nuclei have extremely narrow resonances and can be employed as an essentially decoherence free quantum system. As a result it is possible to very precisely measure interference effects and gain insight into overlapping mode physics this way. Indeed explaining recent experimental findings required heuristic extensions [3] to well known multi-mode models based on the input-output formalism. In this poster we present a theoretical tool for the ab-initio description of such quantum effects in the overlapping mode regime of cavity QED. By linking methods from scattering theory and quantum noise theory we are able to compute reflection spectra and show the relevance of multi-mode effects in X-ray cavities which go beyond input-output models. Our work builds on and connects to recently developed techniques for multi-mode random lasers [4], non-Markovian cavity QED [5] and mesoscopic scattering in complex nanophotonic systems [6].

We present rigorous optical simulations of the modes present in an ultra-thin solar fuels device. Optical resonances are classified into traveling modes which contribute to the large absorption enhancement in the device and localized modes which mainly contribute to parasitic losses. Using the finite element method we are able to quantify the absorption enhancement of the device and optimise the geometry for an optimal mode distribution within the wavelength range of interest. Through the dependence of the optical resonances on geometrical parameters we are able to draw an analogy for the modes to those of simple analytical systems, thereby obtaining a deeper understanding of the underlying physics. Our simulations show how the absorbed photocurrent density of the ultra-thin solar fuels device can be increased by 5.2 mAcm^-2 (47%). This emphasises the ability for plasmonics to provide absorption enhancement in ultra-thin optoelectronic devices.

The spontaneous emission rate of atoms can be modified due to boundary conditions or by embedding the atoms in media. The modifications due to dielectrics have been well studied [1] in recent decades. We extend this framework to magnetodielectric materials, including those with negative refractive index [2], i.e. materials that exhibit simultaneous negative ε and negative μ.

Strong coupling between light and matter leads to the formation of two new optically active hybrid states. The formed states are polaritonic and separated in energy by the Rabi splitting ℏΩ_R, which magnitude depends on the concentration and the transition dipole moment of the molecule. These states show a dispersive behaviour, which means that their energy and the spectral envelope of the emission are angle dependent. In this work, we studied the dependence of the polaritonic lifetime on the angle between the outgoing light beam and the optical cavity. A homemade setup with moveable excitation and emission branches was built in order to measure the dependence. Tetra-tert-butylperylene in a polystyrene matrix was used as organic dye in the optical cavity. The organic film was deposited on a silver mirror by spincoating and another silver mirror was sputtered on the organic layer to obtain a cavity. All in all, our results suggest that no angle dependence on the cavity lifetime exist as predicted by theory.

Figure: Absorbance and emission spectrum of tetra-tert-butylperylene.

The interaction of electromagnetic waves with a material and their propagation are governed by two parameters, the electric permittivity, ε and the magnetic permeability, μ which determine how the electric and magnetic fields respectively interact with the material. By simply setting either of these parameters to zero for a material, a plethora of interesting effects and counterintuitive physics reveal themselves such as zero refractive index , zero wavenumber, infinite wavelength and phase velocity, which is often described as a “tunneling” or“supercoupling” through an ε = 0 medium.[1] An astounding effect of ENZ media is the ability for ENZ materials to theoretically confine light. If we consider the displacement current, $\vec{J}_{D} = \varepsilon_{0}\varepsilon\frac{d\vec{E}}{\text{dt}}$ when $\varepsilon \rightarrow 0$ it’s clear that $\vec{J}_{D} \rightarrow 0$. If we now consider an ENZ medium with a dielectric inclusion such as an air pocket, it’s evident that the displacement field, $\vec{D} = \varepsilon_{0}\varepsilon\vec{E}$ is zero everywhere except within the dielectric inclusion, effectively confining the light within the ENZ structure. Silveirinha et al.[2] and Alù et al.[3] have independently shown that a spherical ENZ shell with a dielectric inclusion can support solutions to Maxwell’s equations that are confined to a region of space irrespective of whether the region is bounded or not. Engheta at al. took this further and have theoretically demonstrated that this is independent of the geometry of the ENZ shell and have suggested that ENZs may lead to the development of geometry-invariant resonant cavities. [4] Another well documented effect of ENZ materials is near-perfect absorption (NPA). NPA has been theoretically and experimentally demonstrated by Yoon et al. in multilayer thin films of ITO on a metallic substrate, shown in Figure 2 below. In an ENZ material, such as ITO at the ENZ wavelength, the normal electric field becomes very strong as it couples to a radiative bulk plasmon mode known as a Berreman mode which results in NPA of ~100%, exceeding the limit of A = 50% for a free-standing thin film. We report the design and fabrication of a structure composed of a thin film of PtSe₂ sandwiched between a thin film of ITO superstrate and a bulk SiO₂ substrate, which has been theoretically shown to excite a Ferrel-Berreman mode of ITO at ~1250 nm and to exhibit near-perfect absorption of light at this ENZ wavelength, similar to that observed by Yoon et al. [5] Our devices has also been shown, via transfer matrix simulations, to exhibit slow light as low as 10^-3 of the speed of light in vacuum. These factors would make our device an ideal candidate for use in the design of a novel near-field transducer. The high thermal stability of ITO in such a device makes it a better alternative as an NFT compared to commonly used plasmonic materials such as gold which undergo severe thermal degradation.

Fig. 1. Theoretical demonstration by Engheta et al. of 3D cavities supporting spatially electrostatic modes with the same eigenfrequency in ENZ structures of various geometries. [4]	Fig. 2. Theoretical and experimental demonstration of near-perfect broadband absorbtance in multilayer ITO thin-films as reported by Yoon et al. [5]

The ground state of the diatomic molecules in nature is inevitably bonding, and its first excited state is antibonding. We demonstrate theoretically that, for a pair of distant adatoms placed buried in three-dimensional-Dirac semimetals, this natural order of the states can be reversed and an antibonding ground state occurs at the lowest energy of the so-called bound states in the continuum. We propose an experimental protocol with the use of a scanning tunneling microscope tip to visualize the topographic map of the local density of states on the surface of the system to reveal the emerging physics.

Most theoretical studies for correlated light-matter systems are performed within the long-wavelength limit, i.e., the electromagnetic field is assumed to be spatially uniform. In this limit the so-called length-gauge transformation for a fully quantized light-matter system gives rise to the dipole self-energy of the electrons. In practice this term is often discarded as it is assumed to be subsumed in the kinetic energy term. In this presentation we show the necessity of the dipole self-energy term. First and foremost, without it the light-matter system in the long-wavelength limit does not have a ground-state. Further implications of the dipole self-energy will be presented, such as the change of the translation operator and how this influences the Bloch theorem.

X-rays are employed across a wide range of industrial sectors and research fields, with applications ranging from airport security to medical radiography. Therefore, the development of efficient and ultra-compact X-ray sources with highly directional output is a long-standing goal in physics. A new approach addressing this challenge was recently proposed[1], where the interaction between graphene plasmons and relatively low-energy electrons generated highly-directional X-ray photons. In that scheme, the high confinement of graphene plasmons is the key property that enables modestly relativistic electrons to generate mono-energetic hard X-rays. Here, we show that the localized surface plasmon resonance of a metasurface, excited by a few-cycle optical pulse, contains high-order spatial harmonics, which interacts with modestly relativistic electrons to efficiently generate multi-harmonic hard X-rays. Moreover, the metasurface geometry and the optical pulse properties are powerful knobs to control and optimize the properties of the high-order spatial harmonics, resulting in a tunable source of multi-harmonic radiation. These conclusions are supported by our analytical formulation, in excellent agreement with ab initio simulations. As an example, we design a multi-color hard X-ray source, potentially useful as a mean to investigate electron transition dynamics, and could be useful in imaging techniques such as multiple-wavelength anomalous diffraction.

Detecting single photons and understanding photons detection are key challenges in quantum optics. One of the most promising technologies for fast, noise-free photon detection in the infrared are superconducting nanowire single-photon detectors (SSPDs). These SSPDs consist of a thin and narrow strip of a superconducting material cooled below the superconducting critical temperature. When a bias current is applied to the nanowire a transition to the normal state can be induced by absorption of a photon of sufficient energy and generates a measurable voltage pulse that is detected as a count. We perform quantum detector tomography measurements on nanofabricated NbN constrictions to extend our understanding of the detection mechanism. Detector tomography is an agnostic method based on the Positive-Operator Valued Measure formalism and translates measured count rates as a function of the average number of photons to a quantum detector response in the photon number basis. We find a linear relation between the current needed to achieve efficient (>1%) detection probability and the energy of the absorbed photons with a surprising offset at zero energy. These observations can be explained by models that combine diffusion of quasiparticles and a photon-assisted vortex entry at the edge of the wire. The photon-assisted vortex model predicts that the edges of the wire are more efficient when detecting photons. Polarization depend detector tomography experiments are consistent with this idea and allow to deduce a position-dependent single photon detection efficiency from the experimental data. We present additional data on the temperature dependence of the detection process to reveal the role of a Berezinskii-Kosterlitz-Thouless transition that limits detections above T/T_c = 0.8. We explore the role of power fluctuations in detector tomography and discuss the direct observation of polarization dependent multi-photon events in the measurements and breakdown of the model for higher photon energies.

We investigate a dissipative tripartite atom-cavity-optomechanical system. We focus on the configuration where the two-level system and the cavity mode are assumed to be in the ultrastrong coupling regime, while the mechanical part interacts with the confined electromagnetic field via the standard optomechanical coupling. We explore the nontrivial ground state structure of such a hybrid system, which hosts a coherent phonon occupation. While in the steady-state this population remains virtual and therefore the system does not emit real phonons, our work explores the possibility to extract real and coherent excitations from the mechanical mode by a non-adiabatic quench of the atom-cavity interaction. We finally study the dependence of the extracted phonon population on the initial coupling strength and the switching amplitude. Our analysis shows that an indirect dynamical Casimir effect occurs where, thanks to the tripartite nature of the system, a perturbation of the atom-cavity system indirectly triggers the emission of phonons.

Figure: Real phonon population produced in the mechanical resonator of the tripartite system by modulating the qubit-optical resonator coupling strength. Here the real phonon occupation is plotted in function of the initial and increase of the atom-cavity coupling strength respectively $g_{a}^{i}$ and $\mathrm{\Delta}g_{a}$.

Colloidal perovskite nanoplatelets, L₂[ABX₃]_n−1BX₄, are a promising class of semiconductor nanomaterials, exhibiting bright luminescence, tunable and spectrally narrow absorption and emission features, strongly confined excitonic states, and facile colloidal synthesis.^[1] Here, we demonstrate their extensive spectral tunability by changing the chemical constituents and nanoplatelet thickness, where L is an organic ligand (butyl-ammonium, octylammonium), A is a monovalent cation (cesium, methyl­ammonium, formamidinium), B is a divalent metal cation (lead, tin), X is a halide anion (chloride, bromide, iodide), and n-1 is the number of perovskite unit cells in thickness. We show that variation of n, B, and X leads to large changes in absorption and emission energy, from the deep UV, across the visible, into the near-IR. On the other hand, changing L, A, or the solvent leads to only subtle changes but can significantly impact the nanoplatelet stability and PLQY with values of up to 22%, outperforming previously reported values. Furthermore, using mixed halide (X) compositions allows a continuous spectral tunability over a 1.5 eV spectral range, from 2.2 eV to 3.7 eV. Using TEM, SEM and XRD, we show that nanoplatelets have large lateral dimensions (100 nm – 1 μm), which promote self-assembly into stacked superlattice structures – the periodicity of which can be adjusted based on the nanoplatelet surface ligand length. With focus on the most quantum confined thicknesses, n = 1 and n = 2, we demonstrate the versatility of colloidal perovskite nanoplatelets as a material platform, with tunability extending from the deep UV, across the visible, into the near-IR. In particular, the tin-containing nanoplatelets represent a significant addition to the small but increasingly important family of lead- and cadmium-free colloidal semiconductors.^[2,3]

Figure: Perovskite nanoplatelets of thicknesses n = 2 and photograph of perovskite nanoplatelets with different chemical compositions and thicknesses (A = organic cation, B = metal, X = halide, n = thickness).

In the present work, we focused on the thermal conductivity and viscosity of the synthesis as well as characterize metal oxide α-Al₂O₃ nanoparticles suspended in distilled water (DW): ethylene glycol (EG) (60:40) ratio based stable colloidal nanofluid. The band gap of the α-Al₂O₃ with and without surfactant is 4.42eV and 4.59eV, respectively. The results show that polyvinyl alcohol (PVA) surfactant having smaller crystalline size (~23 nm) then without surfactant has large (~36 nm). The synthesized nanofluids have good stability after 15 days of synthesis which is characterized by zeta potential analyzer. Thermal conductivity and viscosity are measured for 0.1 wt. % and 0.5 wt. % concentration of alumina for with and without surfactant. The concentration of particles and added surfactant are responsible for stable fluid, increased thermal conductivity and viscosity of nanofluid with respect to temperature. Therefore, the novel combinations of characterized properties of α-Al₂O₃ nanofluid proven the best thermally stable heat transfer fluid compare to conventional cooling fluids.

Organic polaritons are hybrid light-matter states that present several advantages with respect to semiconductor polaritons. Among them, they present larger binding energies and allow for larger Rabi splitting. For a deeper understanding, the study of the dynamics of these systems is desirable, and little is known about their non-Markovian dynamics. In particular, the excitation from the groundstate of the system to the polaritonic states is the first step in any experiment and its modelling is the target of our work. To that purpose, the use of tensor network states is a fascinating tool that allows exact propagation of the system, treating thousands of degrees of freedom (plasmonic, phoninic and radiative) on an equal foot. In this work, we show the results of the simulation of a prototype organic molecule (Rhodamine800) that is excited with a coherent multimode laser field. To see how the absorption spectrum changes we do a scan over the central frequency of the pulse and we analyse the influence of the phononic degrees of freedom.

Carbon nanotubes (CNTs), discovered by S. Iijima (1991), possess exceptional physic-mechanical, electronic, electrical, chemical, thermal, optical etc. properties [1]. Moreover these nanomaterial have chiral nanostructure and semiconductors or metallic behavior, depending on structure and electrical field applied. CNTs, play an important role in many different areas of technique, engineering, transistors, electronics, optics and so on, [2]. Recently has been established that these nanomaterials are very useful tool for treatment of cancer especially for leukemia, [3]. So, all these facts mentioned above, show that study of CNTs has perspective and useful future effects. The aim of the work, presented could be formulated as follows: 1) To develop a theoretical model, background on the computational studies for electronic properties of carbon naotubes; 2) To develop a new theoretical model, and computational one of carbon nanotubes’ optical properties By numerical author’s algorithms and numerical FORTRAN programs, have been investigated the effects of different model’s characteristics, defined electronic and optical properties of carbon nanotubes. Comparison by experiments, shows a good agreement with theoretical (computational) results of the work presented. Graphics, reflecting the results have been given as well.

The process of energy transfer in organic molecules has been extensively studied in the frame of the Förster mechanism, as a result of the dipole-dipole interactions between molecules. Their short-range character limits the typical range to about 10 nm. As recently experimentally demonstrated by Zhong et al [1], this limit can be overcome by strongly coupling the molecules to a cavity mode. Here, we shed light into the physical mechanism that allows excitation transfer of the acceptor molecules even for physical separations from the donor molecules of 100 nm or more. Thanks to the appearance of polaritons (delocalized hybrid light-matter states extended over the entire system) in the strong coupling regime and the resulting mixing of donor and acceptor states with the cavity, non-local energy transfer can be driven by local non-radiative processes [2]. We demonstrate and study this effect based on Bloch-Redfield theory, which allows to reproduce the effect of a complex vibrational bath.

Strong coupling of a dense collection of organic molecules with the electromagnetic modes of nanophotonic and/or plasmonic devices holds great interest for a wide variety of applications. Currently, most theoretical models of such devices use strongly simplified models for at least one of their constituents, typically either treating the molecules as two-level systems, or describing the photonic environment through a single bosonic mode. We here implement an intermediate approach where both complex molecular dynamics as well as arbitrary photonic mode structures can be treated directly. This approach is based on the Maxwell-Bloch approximation using a multi-level description of the molecules. We first treat a simple one-dimensional model to compare and evaluate the respective strengths and weaknesses of a fully classical, a fully quantum and a Maxwell-Bloch approach. We then investigate which effects in organic polaritonics and polaritonic chemistry can be represented within the mean-field description inherent in the Maxwell-Bloch approximation.

The Runge-Gross theorem as the conceptual basis of tdCDFT is based on a force balance equation from which the existence of a unique mapping between potentials (including a vector potential) on the one side and one-particle densities and currents on the other side is derived. Since tdCDFT is expected to solve important problems that persist in tdDFT (without regarding vector potentials and currents) the study of this force equation is of special interest. Here we use the force balance equation to derive approximate exchange-correlation potentials that obey basic conditions such as zero-force and zero-torque. Such approximations will be useful in the calculation of dynamical properties of many-particle systems.

Device miniaturization of functional optical circuits has been shown to be a prerequisite for aiming high efficient, small-footprint devices in sensing^1,2 and communication³. We study the synchronous and phase matching state of two simultaneously excited propagating plasmonic gap modes and demonstrate power-controllable and coherent waveguide feeding with high coupling efficiency of up to 17%. The combination of the subwavelength waveguides separation distance and its ultra-compact pair of coupling nanoantennas enables efficient shaping of the power distribution routed through the double slot waveguide system. Furthermore, experiments show a 10 % increase of the free-space coupling efficiency compared to single antenna systems. Finally, it is demonstrated that this system is well suited to being used as an ultra-compact branchless Mach-Zehnder interferometer device with the capability of loss discrepancies compensation. Thus, the proposed system opens up new possibilities for highly-sensitive and ultra-compact sensing applications.

Figure: (a) Three-dimensional rendering of the proposed parallel plasmonic slot waveguides fed by a pair of optical-loaded nanoantennas with side reflectors at the input and output ports. (b) Schematic cross-section of the device.

During the last years, it has been shown in lots of publications that surface enhanced infrared absorption (SEIRA) spectroscopy is a powerful tool to study minute amounts of molecules or particles on the basis of enhanced vibrational signals. In order to improve sensitivity, the impact of the structures’ geometry as well as their interaction have been investigated.^1–3 Here, we present an experimental work which is focused on the impact of plasmonic nanoantennas’ metal-optical properties on SEIRA. Various geometries of cuboid nanoantennas have been prepared in arrays by means of standard electron beam lithography. To tune the metal-optical properties, we used the metals gold, silver, copper, aluminum, and iron. From the fundamental plasmonic resonance, the contribution of the intrinsic damping (electronic scattering) as well as of the radiative damping were evaluated separately. For a thin organic probe layer on the different antennas, we determined SEIRA enhancement factors. So, our investigation yields a correlation between the ratio of intrinsic damping and radiation damping with SEIRA enhancement which clearly shows the maximum enhancement when both damping mechanisms contribute equally. Finally, we provide recommendations which metal and geometry should be used for highest SEIRA enhancement.

Pigments based color filters absorbed the certain spectrum of light and reflect the remaining portion of light. These kind of color printing have low resolution, thicker in size and degradable with time. Plasmonics based color printing can be treat as solution, where light interact with nanostructure at subwavelength scale. Certain portion of light is reflected based on the size and periodicity of artificially designed nano structures. The structural printing concept is inspired by observations in nature, such as morpho butterflies, beetles, and the feathers of peacocks. In this work, we presented a new approach to achieved high quality of colors using cross shaped Si nanoantennas. We interplayed with Mie resonances in Si nanoantenna to achieve a single narrow resonances throughout the visible range, which results in high quality of primary colors. We numerically predict and experimentally demonstrated the series of high quality of colors by adjusting the size and periodicity of cross-shaped nanoantennas.

We used semiconductor TiO2 colloids as base material for microswimmers owing to efficient activity, environmental benigity, low-cost and chemical stability. Here, we try to elucidate how the fuel and irradiation conditions influence the gradients around the particles which translate into motion. These conditions were probed by traditional analytics as well as using passive colloids as probes.

Novel experiments in cavity QED is at the interface between quantum optics and chemistry. Ab initio methods that treats an interacting many-electron system coupled to photons on an equal quantized footing has been developed and it’s termed Quantum-Electrodynamical Density-Functional theory (QEDFT) [1]. The Kohn-Sham scheme of QEDFT has been used to study ground-state properties of an interacting electron-photon system [2]. Here, we present an ab-initio linear-response (LR) formalism that allows to calculate excited states phenomena for general matter-photon coupled systems. Beside the usual density-density response function known in time-dependent DFT, we have three new response functions due to coupling matter to photons. We reformulate the response functions and develop a numerically feasible and tractable pseudo-eigenvalue problem for the coupled electron-photon system. We present first principle calculations for excited state properties for a specific molecule coupled to a cavity photon.

Recent studies demonstrated considerable interest in plasmonic nanoparticles as nanoscale heat sources for different applications. However, there are limitations with their applicability governed by skin-layer effect and presence of only localized plasmon resonance. In this study, we reveal theoretically and prove experimentally novel concept for non-plasmonic effective optical heating [1]. Contrary to plasmonics, the interaction of light with dielectric or semiconductor nanoparticles of small imaginary part of the permittivity leads to localization of the electromagnetic field inside them. For certain high-Q resonances, it turns out that our optical heating approach is more effective and spectrally broadband than plasmonic one. In addition, non-plasmonic nanoparticles demonstrate temperature dependent optical feedback, which allows to control local temperature more precise and simultaneously with heating via thermally-dependent Raman scattering. Moreover, will be revealed possible applications of this concept such as real-time tracing of molecular events [2] and temperature-feedback direct laser reshaping of dielectric metasurfaces [3].