We demonstrate spin polarized jets in extended systems of ballistic exciton-polariton condensates in semiconductor microcavities using optical non-resonant excitation geometries. The structure of the spin jets is determined by the digitally reprogrammable, spatially non-uniform, degree of circular polarization of the excitation laser. The presence of the laser excitation, strong particle interactions, and spin-relaxation leads to a tunable spin-dependent potential landscape for polaritons, with the appearance of intricate polarization patterns due to coherent matter-wave interference. Our work realizes polarization-structured coherent light sources in the absence of gauge fields.
In a proposed book chapter surface plasmon polariton assisted optical switching in noble metal nanoparticle systems is discussed in the sub-band gap formalism.
Exciton polaritons in semiconductor microcavities exhibit many fundamental physical effects, with some of them amenable to being controlled by external fields. The polariton transport is affected by the polaritonic spin-orbit interaction, which is caused by the splitting of transverse-electric and transverse-magnetic (TE-TM) modes. This is the basis for a polaritonic Hall effect, called optical spin Hall effect (OSHE), which is related to the formation of spin/polarization textures in momentum space, determining anisotropic ballistic transport, as well as related textures in real space. Owing …
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…
Strong light-matter interaction enriches topological photonics by dressing light with matter, which provides the possibility to realize tuneable topological devices with immunity to defects. Topological exciton polaritons, half-light half-matter quasiparticles with giant optical nonlinearity represent a unique platform for active topological photonics with phase tunability. Previous demonstrations of exciton polariton topological insulators still demand cryogenic temperatures and their topological properties are usually fixed without phase tunability. Here, we experimentally demonstrate a room…
The low sensitivity of photons to external magnetic fields is one of the major challenges for the engineering of photonic lattices with broken time-reversal symmetry. Here we show that time-reversal symmetry can be broken for microcavity polaritons in the absence of any external magnetic field thanks to polarization dependent polariton interactions. Circularly polarized excitation of carriers in a micropillar induces a Zeeman-like energy splitting between polaritons of opposite polarizations. In combination with optical spin-orbit coupling inherent to semiconductor microstructures, the interac…
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 propose a scheme of an optical amplifier based on GaN and ZnO waveguides operating in the regime of strong coupling between photonic modes and excitonic resonances. Amplification of the guided exciton-polaritons is obtained by stimulated scattering from the excitonic reservoir, which is found to be fast enough compared with the large velocity of the guided polariton modes. We analyze the device parameters at different temperatures. We find that an 80 $μ$m-long amplifier can provide a gain of 10dB at room temperature, being supplied by 5 mA current in the $cw$ regime.
Optically reconfigurable canalization of exciton-polaritons in a non-hyperbolic perovskite
Nanyang Technological University（南洋理工大学）；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）；Institut Universitaire de France (IUF)（法兰西学院）；National University of Singapore（新加坡国立大学）
Optical field interacting with a topologically protected one-dimensional helical state is shown to support a one-dimensional plasmon-polariton that is characterized by a non-linear dispersion. In a two-dimensional Dirac magnet these electro-optical excitations are confined to domain walls, thus, offering a possibility to manipulate quantum optical states by altering magnetic domain configurations. An exact spectral equation for such a topological plasmon-polariton is derived.
The coherence of polaritons plays a fundamental role in numerous recent experimental observations, from strong coupling to Bose-Einstein condensation, but accessing the coherence of polaritons is a difficult task due to the high energy of plasmons and excitons. However, surface phonon polaritons offer similar promises at much lower energy. Here, we demonstrate the possibility to use visible ultrafast lasers to generate and time resolve coherent surface phonon polaritons in nanowires. We show that these modes are generated through the ultrafast screening of the surface depletion field. By compa…
Van der Waals heterostructures assembled from layers of 2D materials have attracted considerable interest due to their novel optical and electrical properties. Here we report a scattering-type scanning near field optical microscopy study of hexagonal boron nitride on black phosphorous (h-BN/BP) heterostructures, demonstrating the first direct observation of in-plane anisotropic phonon polariton modes in vdW heterostructures. Strikingly, the measured in-plane optical anisotropy along armchair and zigzag crystal axes exceeds the ratio of refractive indices of BP in the x-y plane. We explain that…
We present a microcavity structure with a shifted photonic stop-band to enable efficient non-resonant injection of a polariton condensate with spectrally broad femtosecond pulses. The concept is demonstrated theoretically and confirmed experimentally for a planar GaAs/AlGaAs multilayer heterostructure pumped with ultrashort near-infrared pulses while photoluminescence is collected to monitor the optically injected polariton density. As the excitation wavelength is scanned, a regime of polariton condensation can be reached in our structure at a consistently lower fluence threshold than in a sta…
The nonlinear optical response of organic polaritonic matter has received increasing attention due to their enhanced and controllable nonlinear response and their potential for novel optical devices such as compact photon sources and optical and quantum information devices. Using z-scans at different wavelengths and incident powers we have studied the nonlinear optical dispersion of ultrastrongly coupled organic cavity polaritons near the lower polariton band. We show that the up to 150-fold enhancement of the nonlinear response compared to a cavity-less organic film arises from an intensity-d…
We study optical harmonic generation on the 1S exciton-polariton in the semiconductor ZnSe. Intense and spectrally narrow exciton resonances are found in optical second (SHG), third (THG), and fourth (FHG) harmonic generation spectra. The resonances are shifted to higher energy by 3.2 meV from the exciton energy in the linear reflectivity spectrum. Additional resonances are observed in the THG and FHG spectra and assigned to combinations of incident and backscattered photons in the crystal. Rotational anisotropy diagrams are measured and further information on the origin of the optical harmoni…
Interactions of few-cycle terahertz pulses with the induced optical polarization in a quantum-well microcavity reveal that the lower and higher exciton-polariton modes together with the optically forbidden 2p-exciton state form a unique Λ-type three-level system. Pronounced nonlinearities are observed via time-resolved strong-terahertz and weak-optical excitation spectroscopy and explained with a fully microscopic theory. The results show that the terahertz pulses strongly couple the exciton-polariton states to the 2p-exciton state while no resonant transition between the two polariton levels …
The phase and the frequency of an exciton polariton condensate excited by a nonresonant pump can be efficiently manipulated by an external coherent light. Being tuned close to the resonance with the condensate eigenfrequency, the external laser light imposes its frequency to the condensate and locks its phase, thereby manifesting a synchronization effect. The conditions of formation of the phase synchronized regime are determined. The synchronization of a couple of closely spaced polariton condensates by a spatially uniform coherent light is examined. At the moderate strength of the coherent d…
While optical technology provides the best solution for the transmission of information, optical logics still calls for qualitative new concepts to be explored. Exciton-polaritons are composite particles, resulting from the strong coupling between excitons and photons, which have recently demonstrated exceptional properties like huge non-linearities, long range coherence and suppression of scattering. Here we demonstrate a switching scheme for polaritons moving in the plane of a microcavity which satisfy all the requirements for an all-optical transistor. Under resonant excitation, the power t…
Strong coupling of molecular vibrations to an infrared cavity mode affects their nature by creating dressed polariton states. We show how the single and double vibrational polariton manifolds may be controlled by varying the cavity coupling strength, and probed by a time domain 2DIR technique, Double Quantum Coherence (DQC). Applications are made to the amide-I ($CO$) and amide-II ($CN$) bond vibrations of $N-methylacetamide$ (NMA).
Weyl semimetals possess unique electrodynamic properties due to a combination of strongly anisotropic and gyrotropic bulk conductivity, surface conductivity, and surface dipole layer. We explore the potential of popular tip-enhanced optical spectroscopy techniques for studies of bulk and surface topological electron states in these materials. Anomalous dispersion, extreme anisotropy, and the optical Hall effect for surface polaritons launched by a nanotip provides information about Weyl node position and separation in the Brillouin zone, the value of the Fermi momentum, and the matrix elements…
A simple model, describing the dynamics of the non-equilibrium pseudospin of a homogeneous Bose-Einstein condensate of exciton polaritons, has been formulated. It explains the suppression of spin splitting of a non-equilibrium polariton condensate in an external magnetic field, the optical alignment, and the conversion of alignment into orientation of polaritons. It has been shown that inverse effects are possible, to wit, the spontaneous circular polarization and the enhancement of spin splitting of a non-equilibrium condensate of polaritons in the absence of external field.
Ultrafast Nano-Imaging and Optical Control of Hyperbolic Phonon Polaritons at hBN/WS$_2$ Heterojunctions
Institute for Molecular Science, National Institutes of Natural Sciences（国立自然科学研究所分子科学研究所）；Department of Physics and Electronics, Graduate School of Engineering, Osaka Metropolitan University（大阪公立大学工学研究科物理电子学专业）；The Graduate University for Advanced Studies, SOKENDAI（日本高级研究院）；Research Center for Materials Nanoarchitectonics, National Institute for Materials Science（国立材料研究所物质结构纳米构造研究中心）；Research Center for Electronic and Optical Materials, National Institute for Materials Science（国立材料研究所电子光学材料研究中心）；Fritz-Haber-Institut der Max-Planck-Gesellschaft（马克斯·普朗克学会弗里茨·哈伯研究所）
yperbolic polaritons in van der Waals materials recently attract a lot of attention, owing to their strong electromagnetic field confinement, ultraslow group velocities and long lifetimes. Typically, volume confined hyperbolic polaritons (HPs) are studied. Here we show the first near-field optical images of hyperbolic surface polarities, HSPs, which are confined and guided at the edges of thin flakes of a vdW material. To that end, we applied scattering-type scanning near-field optical microscopy (s-SNOM) for launching and real-space nanoimaging of hyperbolic surface phonon polariton modes on …
We propose an implementation of a CNOT quantum gate for quantum computing based on a patterned microcavity polariton system, which can be manufactured using the modern technological facilities. The qubits are encoded in the spin of polaritons. The structure consists of two wire cavities oriented at 45 degrees with a micropillar between them. The polariton spin rotates due to the Longitudinal-Transverse splitting between polarisation eigenstates in the wires. In the pillar, the optically generated circularly polarised polariton macrooccupied state plays the role of the control qubit. Because of…
We report a theoretical non-equilibrium description of polaritonics and we propose ultrafast all- optical switching due to highly nonlinear polaritonics. The electronic band structure within gold (Au) nano grains is modified by external laser light. The Au grains are coupled to a single mode photonic waveguide and we derive a strong transmission reduction of switching originating from the establishd quantum interference with a finite lifetime.
The precise adjustment of the polariton condensate flow under incoherent excitation conditions is an indispensable prerequisite for polariton-based logic gate operations. In this report, an all-optical approach for steering the motion of a polariton condensate using only non-resonant excitation is demonstrated. We create arbitrarily shaped functional potentials by means of a spatial light modulator, which allow for tailoring the condensate state and guiding a propagating condensate along reconfigurable pathways. Additional numerical simulations confirm the experimental observations and elucida…
We analyse nonequilibrium phase transitions in microcavity polariton condensates trapped in optically induced annular potentials. We develop an analytic model for annular optical traps, which gives an intuitive interpretation for recent experimental observations on the polariton spatial mode switching with variation of the trap size. In the vicinity of polariton lasing threshold we then develop a nonlinear mean-field model accounting for interactions and gain saturation, and identify several bifurcation scenarios leading to formation of high angular momentum quantum vortices. For experimentall…
We calculate the dispersion of spinor exciton-polaritons in a planar microcavity with its active region containing a single Transitional Metal Dichalcogenide (TMD) monolayer, taking into account excitonic and photonic spin-orbit coupling. We consider the radial propagation of polaritons in presence of disorder. We show that the reduction of the disorder scattering induced by the formation of polariton states allows to observe an optical Valley Hall effect, namely the coherent precession of the locked valley and polarization pseudospins leading to the formation of spatial valley-polarized domai…
Exciton-polariton lattices allow to implement topologically protected photonic edge states at optical frequencies. Taking advantage of the interacting character of polaritons, we show that several topological phases, belonging to the Quantum Anomalous Hall family, can occur in polariton graphene with the TE-TM spin-orbit coupling and an effective Zeeman field. This Zeeman field can be entirely controlled by the non-linearity of the macro-occupied mode created by circularly polarized resonant pumping. The topological phases found are distinct from the ones of normal graphene in presence of a co…
By exploiting the polarization multistability of polaritons, we show that polarized signals can be conducted in the plane of a semiconductor microcavity along controlled channels or "neurons". Furthermore due to the interaction of polaritons with opposite spins it is possible to realize binary logic gates operating on the polarization degree of freedom. Multiple gates can be integrated together to form an optical circuit contained in a single semiconductor microcavity.
We report on the experimental realization of an all optical router for exciton-polaritons. This device is based on the design proposed by H. Flayac and I.G. Savenko [APL 103, 201105 (2013)], in which a zero-dimensional island is connected through tunnel barriers to two periodically modulated wires of different periods. Selective transmission of polaritons injected in the island, into either of the two wires, is achieved by tuning the energy of the island state across the band structure of the modulated wires. We show such polariton routing using an optical control beam which blueshifts the isl…
We report experimental evidence of longitudinal optical (LO) phonon-intersubband polariton scattering processes under resonant injection of light. The scattering process is resonant with both the initial (upper polariton) and final (lower polariton) states and is induced by the interaction of confined electrons with longitudinal optical phonons. The system is optically pumped with a mid-IR laser tuned between 1094 cm-1 and 1134 cm-1 (lambda=9.14 um and lambda=8.82 um). The demonstration is provided for both GaAs/AlGaAs and InGaAs/AlInAs doped quantum well systems whose intersubband plasmon lie…
A signature of the scattering between microcavity polaritons and longitudinal optical phonons has been observed in the electroluminescence spectrum of an intersubband device operating in the light-matter strong coupling regime. By electrical pumping we resonantly populate the upper polariton branch at different energies as a function of the applied bias. The electroluminescent signal arising from these states is seconded by a phonon replica from the lower branch.
We propose theoretically an optical diode based on exciton-polaritons in semiconductor microcavities. A flow of polaritons in the bistable regime is used to send signals through an asymmetric fixed potential that favours the tunneling of particles in one direction. Through dynamic modelling of the coherent polariton field, we demonstrate the characteristics of an ideal diode, namely that the forward signal is fully transmitted while the transmission in the reverse direction tends to zero, without any additional external control. Moreover, the system proves to be robust to the presence of disor…
Based on the studies of propagation of an exciton-polariton condensate in a patterned optical microcavity with an embedded graphene layer, we propose a design of a Y-shaped electrically-controlled optical switch. The polaritons are driven by a time-independent force due to the microcavity wedge shape and by a time-dependent drag force owing to the interaction of excitons in graphene and the electric current running in a neighboring quantum well. It is demonstrated that one can control the polariton flow direction by changing the direction of the electric current. The simulations also show that…
We realise bistability in the spinor of polariton condensates under non-resonant optical excitation and in the absence of biasing external fields. Numerical modelling of the system using the Ginzburg-Landau equation with an internal Josephson coupling between the two spin components of the condensate qualitatively describes the experimental observations. We demonstrate that polariton spin bistability persists for sweep times in the range of $[10 μsec,1 sec]$ offering a promising route to spin switches and spin memory elements.
We consider exciton-polaritons in a honeycomb lattice of micropillars subjected to circularly polarized (${σ_\pm}$) incoherent pumps, which are arranged to form two domains in the lattice. We predict that the nonlinear interaction between the polaritons and the reservoir excitons gives rise to the topological valley Hall effect where in each valley two counterpropagating helical edge modes appear. Under a resonant pump, ${σ_\pm}$ polaritons propagate in different directions without being reflected around bends. The polaritons propagating along the interface have extremely high effective lifeti…
We demonstrate deterministic control of the nearest and next-nearest neighbor coupling in the unit cell of a square lattice of microcavity exciton-polariton condensates. We tune the coupling in a continuous and reversible manner by optically imprinting potential barriers of variable height, in the form of spatially localized incoherent exciton reservoirs that modify the particle flow between condensates. By controlling the couplings in a $2\times2$ polariton cluster, we realize ferromagnetic, anti-ferromagnetic and paired ferromagnetic phases. Our approach paves the way towards simulating comp…
We propose an all-optical nonlinear router based on a double barrier gate connected to periodically modulated guides. A semiconductor microcavity is driven nonresonantly in-between the barriers to form an exciton-polariton condensate on a discrete state that is subject to the exciton blueshift. The subsequent coherent optical signal is allowed to propagate through a guide provided that the condensate energy is resonant with a miniband or is blocked if it faces a gap. While a symmetric sample operates as an optical switch, its asymmetric counterpart embodies a router turned to be polarization s…
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…
Topological insulators are a class of electronic materials exhibiting robust edge states immune to perturbations and disorder. This concept has been successfully adapted in photonics, where topologically nontrivial waveguides and topological lasers were developed. However, the exploration of topological properties in a given photonic system is limited to a fabricated sample, without the flexibility to reconfigure the structure in-situ. Here, we demonstrate an all-optical realization of the orbital Su-Schrieffer-Heeger (SSH) model in a microcavity exciton-polariton system, whereby a cavity phot…
We consider a semiconductor polymer chain coupled to a single electromagnetic mode in a cavity. The excitations of the chain have a mixed exciton-photon character and are described as polaritons. Polaritons are coupled to the lattice by the deformation potential interaction and can propagate in the chain. We find that the presence of optical excitation in the polymer induces strain on the lattice. We use a BCS variational wavefunction to calculate the chemical potential of the polaritons as a function of their density. We analyze first the case of a short chain with only two unit cells in orde…
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…
In this paper we reveal the physics behind the formation of tri- and tetra-hyperbolic phases in anisotropic metamaterials without magnetoelectric coupling and describe the anti-crossing splitting phenomenon in the hyperbolic dispersion which arises due to the hybridization of the plasmonic and magnetic Bloch high-k polaritons. This considerably deepens the understanding of the high-k polaritons and the topology of the optical iso-frequency surfaces in k-space and will find applications in optical nano-resolution imaging and emission rate and directivity control. To accomplish this, we develop …
Exciton polaritons in two-dimensional semiconductors inside microcavities are powerful platforms to explore hybrid light-matter quantum systems. Here, we study a macroscopic coherent population of the lowest energy state of polaron-polaritons, which are quasiparticles formed by the dressing of exciton polaritons by particle-hole excitations in a surrounding electron gas. Using a non-perturbative many-body theory to describe exciton-electron correlations combined with a non-equilibrium theory for the macroscopically populated state, we show that the electrons strongly affect the collective prop…
We consider a biased molecular junction subjected to external time-dependent electromagnetic field. The field for two typical junction geometries (bowtie antennas and metal nanospheres) is calculated within finite-difference time-domain technique. Time-dependent transport and optical response of the junctions is calculated within non-equilibrium Green's function approach expressed in a form convenient for description of multi-level systems. We present numerical results for a two-level (HOMO-LUMO) model, and discuss influence of localized surface plasmon polariton modes on transport.
We propose two schemes of a novel spin-optronic device, optical analog of Datta and Das spin transistor for the electrons. The role of ferromagnetic contacts is played by one-dimensional polariton channels with strong TE-TM splitting. A symmetric 2D trap plays a role of the non-magnetic active region. The rotation of the polarization of the pulse in this region can be achieved either due to its interaction with a spatially confined polariton condensate created resonantly by a circular polarized laser, either due to the splitting between the two linear polarizations of the excitons, controlled …
We report on the experimental observation of the non-linear analogue of the optical spin Hall effect under highly non-resonant circularly polarized excitation of an exciton polariton condensate in a GaAs/AlGaAs microcavity. Initially circularly polarized polariton condensates propagate over macroscopic distances while the collective condensate spins coherently precess around an effective magnetic field in the sample plane performing up to four complete revolutions.
Two dimensional semiconductors provide an ideal platform for exploration of linear exciton and polariton physics, primarily due to large exciton binding energy and strong light-matter coupling. These features, however, generically imply reduced exciton-exciton interactions, hindering the realisation of active optical devices such as lasers or parametric oscillators. Here, we show that electrical injection of itinerant electrons into monolayer molybdenum diselenide allows us to overcome this limitation: dynamical screening of exciton-polaritons by electrons leads to the formation of new quasi-p…
