We construct a general theory of adiabatic propagation of spinor exciton-polaritons in waveguides of arbitrary shape, accounting for the effects of TE-TM splitting in linear polarizations and Zeeman splitting in circular polarizations. The developed theory is applied for the description of waveguides of periodically curved shape. We show that in this geometry the periodic rotation of the effective in-plane magnetic field produced by TE-TM interaction results in a nontrivial band-gap structure, which can be additionally tuned by application of an external magnetic field. It is also demonstrated, that spin-dependent interactions between polaritons lead to the formation of stable gap solitons.
We introduce a polariton-waveguide structure, comprised of a nanowire-based photonic crystal waveguide with a quantum dot embedded in each unit cell. Using realistic designs and parameters, we derive and calculate the fundamental electromagnetic properties of these polariton waveguides, with an emphasis on the photon Green function and local optical density of states (LDOS). Both infinite and finite-size waveguides are considered, where the latter's properties are calculated using a Dyson equation approach without any approximations. We demonstrate dramatic increases, and rich fundamental cont…
We demonstrate edge-emitting exciton-polariton (polariton) lasing from 5 to 300 K and amplification of non-radiative guided polariton modes within ZnO waveguides. The mode dispersion below and above the lasing threshold is directly measured using gratings present on top of the sample, fully demonstrating the polaritonic nature of the lasing modes. The threshold is found to be similar to that of radiative polarions in planar ZnO microcavities. These results open broad perspectives for guided polaritonics by allowing an easier and more straightforward implementation of polariton integrated circu…
We report on novel exciton-polariton routing devices created to study and purposely guide light-matter particles in their condensate phase. In a co-directional coupling device, two waveguides are connected by a partially etched section which facilitates tunable coupling of the adjacent channels. This evanescent coupling of the two macroscopic wavefunctions in each waveguide reveals itself in real space oscillations of the condensate. This Josephson-like oscillation has only been observed in coupled polariton traps so far. Here, we report on a similar coupling behavior in a controllable, propag…
Weyl semimetals have recently attracted extensive attention due to their anomalous band structure manifested by topological properties that lead to some unusual and unique physical properties. We investigate novel features of surface plasmon polaritons in a slot waveguide comprised from two semi-infinite Weyl semimetals. We consider symmetric Voigt-Voigt and Faraday-Faraday configurations for plasmon polaritons in two interfaces of waveguide and show that the resulting dispersion is symmetric and the propagation of surface plasmon polaritons is bidirectional. We introduce exotic and novel asym…
We photo-excite slab polymer waveguides doped with J-aggregating dye molecules and measure the leaky emission from strongly coupled waveguide exciton polariton modes at room temperature. We show that the momentum of the waveguide exciton polaritons can be controlled by modifying the thickness of the excitonic waveguide. Non-resonantly pumped excitons in the slab excitonic waveguide decay into transverse electric and transverse magnetic strongly coupled exciton waveguide modes with radial symmetry. These leak to cones of light with radial and azimuthal polarizations.
We theoretically investigate the electronic transport properties of curved graphene waveguides by employing non-equilibrium Green's function techniques. We systematically study the dependence of the confined waveguide modes on the potential difference, the width of waveguide and side barrier. Through two-terminal electronic transport calculations, we show that the conductance of confined waveguide modes is rather robust against the bending degree of waveguide, in consistent with the band insensitivity to the side barrier. This finding of the perfectly conducting channels strongly suggests the …
The peculiar topological properties of Weyl semimetals (WSMs) lead to unusual and unique optical properties. We investigate novel features of surface plasmon polaritons (SPPs) in a slot waveguide comprised of two semi-infinite WSMs with different symmetries, one with broken time reversal symmetry (TRS) and the other with broken inversion symmetry. We consider Voigt and Faraday configurations for SPPs at the interface of the WSM with broken TRS. We demonstrate that in the Voigt configuration this structure supports unidirectional SPP modes above the bulk plasmon frequency while it shows a non-r…
We investigate the demonstration and quantification of the strong coupling between excitons and guided photons in a GaN slab waveguide. The dispersions of waveguide polaritons are measured from T=6~K to 300~K through gratings. They are carefully analyzed within four models based on different assumptions, in order to assess the strong coupling regime. We prove that the guided photons and excitons are strongly coupled at all investigated temperatures, with a small $(11 \%)$ dependence on the temperature. However the values of the Rabi splitting strongly vary among the four models: the "coupled o…
We consider a two-dimensional extension of the 1D waveguide quantum electrodynamics and investigate the nature of linear excitations in two-dimensional arrays of qubits coupled to networks of chiral waveguides. We show that the combined effects of chirality and long-range photon mediated qubit-qubit interactions lead to the emergence of the two-dimensional flat bands in the polaritonic spectrum, corresponding to slow strongly correlated light.
We study the unconventional topological phases of polaritons inside a cavity waveguide, demonstrating how strong light-matter coupling leads to a breakdown of the bulk-edge correspondence. Namely, we observe an ostensibly topologically nontrivial phase, which unexpectedly does not exhibit edge states. Our findings are in direct contrast to topological tight-binding models with electrons, such as the celebrated Su-Schrieffer-Heeger (SSH) model. We present a theory of collective polaritonic excitations in a dimerized chain of oscillating dipoles embedded inside a photonic cavity. The added degre…
We report on III-nitride waveguides with c-plane GaN/AlGaN quantum wells in the strong light-matter coupling regime supporting propagating polaritons. They feature a normal mode splitting as large as 60 meV at low temperatures thanks to the large overlap between the optical mode and the active region, a polariton decay length up to 100 $μ$m for photon-like polaritons and lifetime of 1-2 ps; with the latter values being essentially limited by residual absorption occurring in the waveguide. The fully lattice-matched nature of the structure allows for very low disorder and high in-plane homogenei…
In the present paper, the collective near-field effects in a two-graphene sheets plasmonic waveguide loaded with an array of Ag$_2$Se quantum dots excited by external radiation are theoretically studied. This research aims to develop a theoretical approach to realizing controllable excitation and the propagation of surface plasmon polaritons (SPPs) in planar graphene waveguides. The proposed model is based on the semiclassical description that implies the dispersion equation's solution for SPPs excited in two coupled graphene sheets and the embedded quantum dots' energy spectra analysis. Using…
Two-dimensional van der Waals (vdW) crystals can sustain various types of polaritons with strong electromagnetic confinements, making them highly attractive for the nanoscale photonic and optoelectronic applications. While extensive experimental and numerical studies are devoted to the polaritons of the vdW crystals, analytical models are sparse. Particularly, applying such a model to describe the polariton behaviors visualized by state-of-art near-field optical microscopy requires further investigation. Herein, we develop an analytical waveguide model to describe the polariton propagations in…
We show that with a system of electrically-gated wide quantum wells embedded inside a simple dielectric waveguide structure, it is possible to excite, control, and observe waveguided exciton polaritons that carry an electric dipole moment. We demonstrate that the energy of the propagating dipolariton can be easily tuned using local electrical gates, that their excitation and extraction can be easily done using simple evaporated metal gratings, and that the dipolar interactions between polaritons and between polaritons and excitons can also be controlled by the applied electric fields. This sys…
We investigate polariton-phonon hybrid excitations, which describe the collective excitations of emitter-photon polaritons and vibrational phonons, in a periodic array of vibrating two-level emitters interacting with waveguide photons. We demonstrate the emergence of an interaction-induced quasiperiodic structure caused by the interplay between phonon scatterings and waveguide-mediated long-range couplings. This quasiperiodicity fundamentally changes the excitation characteristics in the subradiant regime, which feature an appearance of topological edge states and a transition between ergodic …
We study the nonequilibrium exciton-polariton condensation in 1D to 0D and 1D to 2D junctions by means of non-resonant spectroscopy. The shape of our potential landscape allows to probe the resonant transmission of a propagating condensate between a quasi-1D waveguide and cylindrically symmetric states. We observe a distinct mode selection by varying the position of the non-resonant pump laser. Moreover, we study the the case of propagation from a localized trapped condensate state into a waveguide channel. Here, the choice of the position of the injection laser allows us to tune the output in…
Layered topological insulators, for example, Bi$_2$Se$_3$ are optically hyperbolic materials in a range of THz frequencies. Such materials possess deeply subdiffractional, highly directional collective modes: hyperbolic phonon-polaritons. In thin crystals the dispersion of such modes is split into discrete subbands and is strongly influenced by electron surface states. If the surface states are doped, then hybrid collective modes result from coupling of the phonon-polaritons with surface plasmons. The strength of the hybridization can be controlled by an external gate that varies the chemical …
We experimentally demonstrate the propagation of long-range surface plasmon-polaritons in a nobel metal stripe waveguide at an optical wavelength of 780 nm. To minimize propagation damping the lithographically structured waveguide is produced from a thin gold stripe embedded in a dielectric polymer. Our waveguide geometry supports a symmetric fundamental and anti-symmetric first order mode. For the fundamental mode we measure a propagation loss of $(6.12^{+0.66} _{-0.54})$ dB/mm, in good agreement with numerical simulations using a vectorial eigenmode solver. Our results are a promising starti…
Van der Waals (vdW) materials, weakly bound layered compounds, have received enormous interest as they offer a malleable playground for a wide range of physical properties in thermal, electronic and optical devices. In particular, owing to their inherent deep subwavelength light confinement, they support a variety of light-matter interactions phenomena such as plasmons, excitons and phonons conveyed as polaritonic modes. Specifically, semiconductor vdW materials such as WSe_2 are particularly attractive for photonic and quantum integrated technologies since they sustain VIS-NIR exciton-polarit…
The suite of highly confined polaritons supported by two-dimensional (2D) materials constitutes a versatile platform for nano-optics, offering the means to channel light on deep-subwavelength scales. Graphene, in particular, has attracted considerable interest due to its ability to support long-lived plasmons that can be actively tuned via electrical gating. While the excellent optoelectronic properties of graphene are widely exploited in plasmonics, its mechanical flexibility remains relatively underexplored in the same context. Here, we present a semi-analytical formalism to describe plasmon…
The exciton polariton (EP), a half-light and half-matter quasiparticle, is potentially an important element for future photonic and quantum technologies. It provides both strong light-matter interactions and long-distance propagation that is necessary for applications associated with energy or information transfer. Recently, strongly-coupled cavity EPs at room temperature have been demonstrated in van der Waals (vdW) materials due to their strongly-bound excitons. Here we report a nano-optical imaging study of waveguide EPs in MoSe2, a prototypical vdW semiconductor. The measured propagation l…
Exciton-polaritons are hybrid light-matter excitations arising from the non-perturbative coupling of a photonic mode and an excitonic resonance. Behaving as interacting photons, they show optical third-order nonlinearities providing effects such as optical parametric oscillation or amplification. It has been suggested that polariton-polariton interactions can be greatly enhanced by inducing aligned electric dipoles in their excitonic part. However direct evidence of a true particle-particle interaction, such as superfluidity or parametric scattering is still missing. In this work, we demonstra…
Single surface plasmon polaritons are excited using photons generated via spontaneous parametric down-conversion. The mean excitation rates, intensity correlations and Fock state populations are studied. The observed dependence of the second order coherence in our experiment is consistent with a linear uncorrelated Markovian environment in the quantum regime. Our results provide important information about the effect of loss for assessing the potential of plasmonic waveguides for future nanophotonic circuitry in the quantum regime.
Boosting self hybridized exciton polaritons with metal clad WS2 waveguides
Institute of Experimental and Applied Physics, Kiel University（基尔大学实验与应用物理研究所）；Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器研究所鲁普雷希特·亨塞尔实验室）
In recent years, novel materials supporting in-plane anisotropic polaritons have attracted a lot of research interest due to their capability of shaping nanoscale field distributions and controlling nanophotonic energy flows. Here we report a nano-optical imaging study of waveguide exciton polaritons (EPs) in tin sulfide (SnS) in the near-infrared (IR) region using the scattering-type scanning near-field optical microscopy (s-SNOM). With s-SNOM, we mapped in real space the propagative EPs in SnS, which show sensitive dependence on the excitation energy and sample thickness. Moreover, we found …
Soliton formation in a bound state in the continuum GaN waveguide polariton laser
Laboratoire Charles Coulomb, Université de Montpellier, CNRS（蒙彼利埃大学查尔斯·库隆实验室）；Institut Pascal, PHOTON-N2, Université Clermont Auvergne, CNRS, Clermont INP（克莱蒙奥弗涅大学帕斯卡尔研究所）；B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine（乌克兰国家科学院B.维尔金低温物理与工程研究所）；Naturwissenschaftlich-Technische Fakultät, Universität Siegen（锡根大学自然科学技术学院）；CRHEA, Université Cote d’Azur, CNRS（蔚蓝海岸大学CRHEA研究中心）；Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay（巴黎萨克雷大学纳米科学和纳米技术研究中心）
In this work we show that (real space) curvature in the geometry of curved waveguides with Rashba spin orbit interaction (RSOI) can lead to out of plane spin accumulations. We first derive the RSOI Hamiltonian on arbitrarily curved surfaces. We then analyze the effects of curvature with two distinct methods. We first apply an adiabatic approximation on gently curved, planar waveguides lying flat on the $xy$ plane to show that analogous to the acceleration of the charge carriers by an electric field, the change in momentum direction of the charge carriers as they move along the waveguide leads …
We study exciton-polariton nonlinear optical fluids in a high momentum regime for the first time. Defects in the fluid develop into dark solitons whose healing length decreases with increasing density. We deduce interaction constants for continuous wave polaritons an order of magnitude larger than with picosecond pulses. Time dependent measurements show a 100ps time for the buildup of the interaction strength suggesting a self-generated excitonic reservoir as the source of the extra nonlinearity. The experimental results agree well with a model of coupled photons, excitons and the reservoir.
Reversible exchange of photons between a material and an optical cavity can lead to the formation of hybrid light--matter states where material properties such as the work function\cite{Hutchison_AM2013a}, chemical reactivity\cite{Hutchison_ACIE2012a}, ultra--fast energy relaxation \cite{Salomon_ACIE2009a,Gomez_TJOPCB2012a} and electrical conductivity\cite{Orgiu_NM2015a} of matter differ significantly to those of the same material in the absence of strong interactions with the electromagnetic fields. Here we show that strong light--matter coupling between confined photons on a semiconductor wa…
We report on the linear polarization of polariton condensates in a codirectional coupler that allows evanescent coupling between adjacent waveguides. We observe polarization-dependent intensity oscillations in the output terminal of the coupler that we identify as the mode beating between the linear-polarized eigenmodes.
We present a formalism for studying the radiation-matter interaction in multilayered dielectric structures with active semiconductor quantum wells patterned with an in-plane periodic lattice. The theory is based on the diagonalization of the generalized Hopfield matrix, and it includes loss channels in a non-Hermitian formulation. Hybrid elementary excitations named photonic crystal polaritons arise in these systems, whose detailed dispersion and loss characteristics are shown to depend on material composition as well as on symmetry properties of the lattice. We show the generality of the appr…
Emergence of Propagating Exciton-Polaritons in Hybrid Waveguide-van der Waals Heterostructures
Institute of Physics, University of Rostock（罗斯托克大学物理研究所）；Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik (FBH)（费迪南德·布劳恩研究所，莱布尼茨高频技术研究所）；Research Center for Materials Nanoarchitectonics, NIMS（日本物质材料研究机构纳米结构材料研究中心）；Research Center for Electronic and Optical Materials, NIMS（日本物质材料研究机构电子光学材料研究中心）
We have investigated the spectrum of two-dimensional (2D) plasmon polaritons over the full range of magnetic fields. In our study, we investigate a disk-shaped two-dimensional electron system (2DES) with a metallic gate on the backside of the substrate. Importantly, we show that 2D plasmon polaritons hybridize with the TM$_0$ photonic mode of a dielectric waveguide formed by a sample substrate. We have developed a theory for plasmon-polaritons in an infinite 2DES. We find the experimental data to be in good agreement with the developed theory.
The requirement for optical-electrical-optical conversion of signals in optical technologies is often one of the majors bottleneck in terms of speed and energy consumption. The use of dressed photons (also called polaritons), that allows for intrinsic sizable interactions, could significantly improve the performances of optical integrated elements such as switches or optical gates. In this work we demonstrate the ultrafast switch of a laser coupled into a polaritonic waveguide triggered by an optical pulse resonant with the same dispersion but at a lower energy. Our experiments show two effect…
Mode-locking instability and multiple soliton formation in GaN polariton waveguide cavities
Université Clermont Auvergne, CNRS（克莱蒙奥弗涅大学，法国国家科学研究中心）；B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine（乌克兰国家科学院B.维尔金低温物理与工程研究所）；Laboratoire Charles Coulomb, Université de Montpellier, CNRS（蒙彼利埃大学，查尔斯·库隆实验室，法国国家科学研究中心）；Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay（巴黎萨克雷大学，纳米科学与纳米技术研究中心，法国国家科学研究中心）；University Côte d’Azur, CNRS, CRHEA（蔚蓝海岸大学，法国国家科学研究中心，低维系统与高功率电子研究中心）；University of Strathclyde（思克莱德大学）；MajuLab, International Research Laboratory IRL 3654, CNRS, Université Côte d’Azur, Sorbonne Université, National University of Singapore, Nanyang Technological U（MajuLab，国际研究实验室IRL 3654，法国国家科学研究中心，蔚蓝海岸大学，索邦大学，新加坡国立大学，南洋理工大学）
Recently reported large values of exciton-polariton nonlinearity of transition metal dichalcogenide (TMD) monolayers coupled to optically resonant structures approach the values characteristic for GaAs-based systems in the regime of strong light-matter coupling. Contrary to the latter, TMD-based polaritonic devices remain operational at ambient conditions and therefore have greater potential for practical nanophotonic applications. Here we present the study of the nonlinear properties of Ta$_2$O$_5$ slab waveguide coupled to a WSe$_2$ monolayer. We first confirm that the hybridization between …
We study the coherent properties of plasmon polaritons optically excited on periodic nanostructures. The gold grains are coupled to a single mode photonic waveguide which exhibits a dramatically reduced transmission originating from the derived quantum interference. With a nonequilibrium description of Floquet-dressed polaritons we demonstrate the switching of light transmission through the waveguide due to sheer existence of intraband transitions in gold from right above the Fermi level driven by the external laser light.
The nature of trions and their interaction with light has remained a puzzle. The composition and dispersion of polaritons involving trions provide insights into this puzzle. Trions and excitons in doped two-dimensional (2D) materials are not independent excitations but are strongly coupled as a result of Coulomb interactions. When excitons in doped 2D materials are also strongly coupled with light inside an optical waveguide, the resulting polariton states are coherent superpositions of exciton, trion, and photon states. We realize these exciton-trion-polaritons by coupling an electron-doped m…
We present optical investigations of hybrid plasmonic nanosystems consisting of lithographically defined plasmonic Au-waveguides or beamsplitters on GaAs substrates coupled to proximal self-assembled InGaAs quantum dots. We designed a sample structure that enabled us to precisely tune the distance between quantum dots and the sample surface during nano-fabrication and demonstrated that non-radiative processes do not play a major role for separations down to $\sim 10 nm$. A polarized laser beam focused on one end of the plasmonic nanostructure generates propagating surface plasmon polaritons th…
The spectrum of the Laplace operator in a curved strip of constant width built along an infinite plane curve, subject to three different types of boundary conditions (Dirichlet, Neumann and a combination of these ones, respectively), is investigated. We prove that the essential spectrum as a set is stable under any curvature of the reference curve which vanishes at infinity and find various sufficient conditions which guarantee the existence of geometrically induced discrete spectrum. Furthermore, we derive a lower bound on the distance between the essential spectrum and the spectral threshold…
Hyperbolic polaritons in van der Waals materials and metamaterial heterostructures provide unprecedented control over light-matter interaction at the extreme nanoscale. Here, we propose a concept of type-I hyperbolic metasurface supporting highly-squeezed magnetic designer polaritons, which act as magnetic analogues to hyperbolic polaritons in the hexagonal boron nitride (h-BN) in the first Reststrahlen band. Comparing with the natural h-BN, the size and spacing of the metasurface unit cell can be readily scaled up (or down), allowing for manipulating designer polaritons in frequency and in sp…
Exciton-polariton solitons are strongly nonlinear quasiparticles composed of coupled exciton-photon states due to the interaction of light with matter. In semiconductor microcavity systems such as semiconductor micro and nanowires, polaritons are characterized by a negative mass which when combined with the repulsive nonlinear exciton-exciton interaction, leads to the generation of bright polariton solitons. In this work we investigate the dynamics of bright exciton-polariton solitons in a finite-size microcavity waveguide, for which radiative losses are assumed balanced by the external pumpin…
We study the nature of the essential spectrum of the Dirichlet Laplacian in tubes about infinite curves embedded in Euclidean spaces. Under suitable assumptions about the decay of curvatures at infinity, we prove the absence of singular continuous spectrum and state properties of possible embedded eigenvalues. The argument is based on Mourre conjugate operator method developed for acoustic multistratified domains by Benbernou and Dermenjian et al. As a technical preliminary, we carry out a spectral analysis for Schrodinger-type operators in straight Dirichlet tubes. We also apply the result to…
Artifical superlattice (SL) potentials have been employed extensively for band structure engineering of two-dimensional (2D) Dirac electron gas in graphene. While such engineered electronic band structures can modify optical or plasmonic properties of graphene, an emergent polaritonic behavior beyond weak perturbative effects (e.g. anisotropic Drude weights) has not been reported. Here, we show that an extreme modulation of one-dimensional (1D) SL potentials in monolayer graphene deforms the underlying Dirac band dispersion and introduces ladder-like energy levels near the Fermi surface, which…
