Starting from a fully quantized Hamiltonian for an ensemble of identical emitters coupled to the modes of an optical cavity, we determine analytically regimes of thermal, collective anti-bunching and laser emission that depend explicitly on the number of emitters. The lasing regime is reached for a number of emitters above a critical number (which depends on the light-matter coupling, detuning and the dissipation rates) via a universal transition from thermal emission to collective anti-bunching to lasing as the pump increases. Cases where the second order intensity correlation fails to predict laser action are also presented.
The collective spontaneous emission of two point-dipole emitters near a plasmonic core-shell nanosphere is theoretically investigated. Based on the expansion of mode functions in vector spherical harmonics, we derive closed analytical expressions for both the cooperative decay rate and the dipole-dipole interaction strength associated with two point dipoles close to a sphere. Considering a plasmonic nanoshell containing a linearly amplifying medium inside the core, the second-order correlation function for the two emitters shows that it is possible to tune the photon emission, selecting either…
Lasers are ubiquitous for information storage, processing, communications, sensing, biological research, and medical applications [1]. To decrease their energy and materials usage, a key quest is to miniaturize lasers down to nanocavities [2]. Obtaining the smallest mode volumes demands plasmonic nanocavities, but for these, gain comes from only single or few emitters. Until now, lasing in such devices was unobtainable due to low gain and high cavity losses [3]. Here, we demonstrate a plasmonic nanolaser approaching the single-molecule emitter regime. The lasing transition significantly broade…
In a recent Letter [Phys. Rev. Lett. 126, 063902 (2021)], M. A. Carroll et al. derived a model to analytically determine regimes of thermal, collective anti-bunching, and laser emission for emitters in a cavity. According to their model, nanolasers exhibit a distinct threshold at which the coherent laser field emerges from a bifurcation at a finite pump rate. The amplitude of this coherent field increases with a further increase in the pump rate. Such a behavior contrasts the usual view of the transition to lasing in single-mode high-$β$ nanolasers, according to which strong spontaneous emissi…
The impulsive excitation of ensembles of excitons or color centers by a high-energy electron beam results in the observation of photon bunching in the second-order correlation function of the cathodoluminescence generated by those emitters. Photon bunching in cathodoluminescence microscopy can be used to resolve the excited-state dynamics and the excitation and emission efficiency of nanoscale materials, and it can be used to probe interactions between emitters and nanophotonic cavities. Here, we report substantial changes in the measured bunching induced by indirect electron interactions (wit…
Stimulated emission in small-molecule organic films at a high dye concentration is generally hindered by fluorescence quenching, especially in the red region of the spectrum. Here we demonstrate the achievement of high net gains (up to 50 cm-1) around 640 nm in thermally evaporated non-doped films of 4-di(4'-tert-butylbiphenyl-4-yl)amino-4'-dicyanovinylbenzene, which makes this material suitable for green-light pumped single-mode organic lasers with low threshold and superior stability. Lasing effect is demonstrated in a DBR resonator configuration, as well as under the form of random lasing a…
The regime of strong light-matter coupling is typically associated with weak excitation. With current realizations of cavity-QED systems, strong coupling may persevere even at elevated excitation levels sufficient to cross the threshold to lasing. In the presence of stimulated emission, the vacuum-Rabi doublet in the emission spectrum is modified and the established criterion for strong coupling no longer applies. We provide a generalized criterion for strong coupling and the corresponding emission spectrum, which includes the influence of higher Jaynes-Cummings states. The applicability is de…
Measured and calculated results are presented on the emission properties of a new class of emitters operating in the cavity quantum electrodynamics regime. The structures are based on high-finesse GaAs/AlAs micropillar cavities, each with an active medium consisting of a layer of InGaAs quantum dots and distinguishing feature of having substantial fraction of spontaneous emission channeled into one cavity mode (high-beta factor). This paper shows that the usual criterion for lasing with a conventional (low-beta factor) cavity, a sharp nonlinearity in an input-output curve accompanied by notice…
We deconstruct and address a comment to Carroll et al. [Phys Rev Lett 126, 063902 (2021)] (PRL) that has been posted on arXiv appearing as two versions [arXiv:2106.15242v1] and [arXiv:2106.15242v2]. This comment claimed that a term in the model presented in the PRL had been incorrectly omitted and that, hence, the laser threshold predicted by the model in the PRL is unattainable. We show that the term in question was correctly neglected because it represents collective effects that are not observable in the devices modelled in the PRL. Moreover, even if this term were to be included, the laser…
We analyze the second-order photon autocorrelation function $g^{(2)}$ with respect to the photon probability distribution and discuss the generic features of a distribution that result in superthermal photon bunching ($g^{(2)}>2$). Superthermal photon bunching has been reported for a number of optical microcavity systems that exhibit processes like superradiance or mode competition. We show that a superthermal photon number distribution cannot be constructed from the principle of maximum entropy, if only the intensity and the second-order autocorrelation are given. However, for bimodal systems…
We calculate the quantum state of the plasmon field excited by an ensemble of molecular emitters, which are driven by exchange of electrons with metallic nano-particle electrodes. Assuming identical emitters that are coupled collectively to the plasmon mode but are otherwise subject to independent relaxation channels, we show that symmetry constraints on the total system density matrix imply a drastic reduction in the numerical complexity. For $N_{\text{m}}$ three-level molecules we may thus represent the density matrix by a number of terms scaling as $(N_{\rm m}+8)!/(8!N_{\rm m}!)$ instead of…
A long existing issue for microdisk lasers is the small spontaneous emission coupling rate (β) in microdisk,. We found that it is due to the coupling of emitter spontaneous emission into competing Fabry-Perot (FP) modes in the microdisk cavity. Based on this analysis, we propose a new type of photonic crystal microdisk (PCM) laser to drastically suppress the photonic density of states in the vertical FP modes. As a result, we obtained a three fold increase of β than previously reported highest β of 0.15 at room temperature. The spontaneous emission control in truncated photonic crystals become…
We describe a superconducting device capable of producing laser light in the visible range at half the Josephson generation frequency, with the optical phase of the light locked to the superconducting phase difference. An earlier proposed device, the so called "half-Josephson laser" [Phys. Rev. Lett. 107, 073901 (2011)], cannot provide long coherence times, because of spontaneous switchings between the emitter states. To circumvent this we consider N >> 1 emitters driving an optical resonator mode. We derive a general model that captures essential physics of such devices while not depending on…
The implementation of non-classical light sources is becoming increasingly important for various quantum applications. A particularly interesting approach is to integrate such functionalities on a single chip as this could pave the way towards fully scalable quantum photonic devices. Several approaches using dielectric systems have been investigated in the past. However, it is still not understood how on-chip nanoplasmonic antennas, interacting with a single quantum emitter, affect the quantum statistics of photons reflected or transmitted in the guided mode of a waveguide. Here we investigate…
Controlling light-matter interactions in solid-state systems has motivated intense research to produce bosonic quasi-particles known as exciton-polaritons, which requires strong coupling between excitons and cavity photons. Ultra-low threshold coherent light emitters can be achieved through lasing from exciton-polariton condensates, but this generally requires sophisticated device structures and cryogenic temperatures. Polaritonic nanolasers operating at room temperature lie on the crucial path of related research, not only for the exploration of polariton physics at the nanoscale but also for…
Metallic nanostructures provide a toolkit for the generation of coherent light below the diffraction limit. Plasmonic based lasing relies on the population inversion of emitters (such as organic fluorophores) along with feedback provided by plasmonic resonances. In this regime, known as weak light matter coupling, the radiative characteristics of the system can be described by the Purcell effect. Strong light matter coupling between the molecular excitons and electromagnetic field generated by the plasmonic structures leads to the formation of hybrid quasi-particles known as plasmon exciton po…
Room Temperature Collective Blinking and Photon Bunching from CsPbBr3 Quantum Dot Superlattice
Institute of Science Tokyo（东京科学大学）；Katholieke Universiteit Leuven（荷语鲁汶大学）；Lingnan Normal University（岭南师范学院）；Max Planck Institute for Polymer Research（马克斯·普朗克聚合物研究所）
Light emitters are bound to strongly interact with light through enhanced absorption and scattering, which imposes limitations on the design and performance of photonic devices such as solar cells, nanoantennas, and (nano) lasers. Overcoming these limitations forces the use of ineffective nonreciprocity approaches or separation of radiation and scattering in the frequency or time domain. A design that combines the properties of an efficient emitter in one state and the property of being invisible in another state is vital for various applications. In this work, we propose a nanolaser design ba…
The use of virtually lossless topologically isolated edge states may lead to a novel class of thresholdless lasers operating without inversion. One needs however to understand if topological states may be coupled to external radiation and act as active cavities. We study a two-level topological insulator and show that self-induced transparency pulses can directly excite edge states. We simulate laser emission by a suitable designed topological cavity, and show that it can emit tunable radiation. For a configuration of sites following the off-diagonal Aubry-Andre-Harper model we solve the Maxwe…
We present an experimental and theoretical study on the gain mechanism in a photonic-crystal-cavity nanolaser with embedded quantum dots. From time-resolved measurements at low excitation power we find that four excitons are coupled to the cavity. At high excitation power we observe a smooth low-threshold transition from spontaneous emission to lasing. Before lasing emission sets in, however, the excitons are observed to saturate, and the gain required for lasing originates rather from multi-electronic transitions, which give rise to a broad emission background. We compare the experiment to a …
We extend Lamb's reduced density matrix laser theory to analyze the inhomogeneous molecular couplings and the mode-correlation in a plasmonic nano-laser consisting of a gold sphere and many dye molecules interacting with a driving optical field and with the quantized plasmon modes. The molecular inhomogeneity is accounted for by simulating their random distribution around the sphere. Our analysis shows that in order to obtain lasing we must employ a large number of strongly driven molecules to compensate strong damping of the plasmon modes. The compact molecular arrangement, however, can lead …
Dicke superradiance is an example of emergence of macroscopic quantum coherence via correlated dissipation. Starting from an initially incoherent state, a collection of excited atoms synchronizes as they decay, generating a macroscopic dipole moment and emitting a short and intense pulse of light. While well understood in cavities, superradiance remains an open problem in extended systems due to the exponential growth of complexity with atom number. Here we show that Dicke superradiance is a universal phenomenon in ordered arrays. We present a theoretical framework -- which circumvents the exp…
GeSn alloys are the most promising semiconductors for light emitters entirely based on group IV elements. Alloys containing more than 8 at.% Sn have fundamental direct band-gaps, similar to conventional III-V semiconductors and thus can be employed for light emitting devices. Here, we report on GeSn microdisk lasers encapsulated with a SiNx stressor layer to produce tensile strain. A 300nm GeSn layer with 5.4 at.% Sn, which is an indirect band-gap semiconductor as-grown with a compressive strain of -0.32 %, is transformed via tensile strain engineering into a truly direct band-gap semiconducto…
We report on experimental study into the effects of surface acoustic waves on the optical emission of dot-in-a-nanowire heterostructures in III-V material systems. Under direct optical excitation, the excitonic energy levels in III-nitride dot-in-a-nanowire heterostructures oscillate at the acoustic frequency, producing a characteristic splitting of the emission lines in the time-integrated photoluminescence spectra. This acoustically induced periodic tuning of the excitonic transition energies is combined with spectral detection filtering and employed as a tool to regulate the temporal output…
Optical nanostructures have proven to be meritorious for tailoring the emission properties of quantum emitters. However, unavoidable fabrication imperfections may represent a nuisance. Quite remarkably, disorder offers new opportunities since light can be efficiently confined by random multiple scattering leading to Anderson localization. Here we investigate the effect of such disorder-induced cavities on the emission dynamics of single quantum dots embedded in disordered photonic-crystal waveguides. We present time-resolved measurements of both the total emission from Anderson-localized cavit…
We investigate the spatial and spectral properties of broad-area vertical-cavity surface-emitting lasers (VCSEL) with frequency-selective feedback by a volume Bragg grating (VBG). We demonstrate wavelength locking similar to the case of edge-emitters but the spatial mode selection is different from the latter. On-axis spatial solitons obtained at threshold give way to off-axis extended lasing states beyond threshold. The investigations focus on a self-imaging external cavity. It is analyzed how deviations from the self-imaging condition affect the pattern formation and a certain robustness of …
We report single plasmon generation with a self-assembled InAs/GaAs quantum dot embedded in a plasmonic microring resonator. The plasmonic cavity based on a GaAs microring is defined on an atomically-smooth silver surface. We fabricated this structure with the help of transfer printing, which enables the pick-and-place assembly of the complicated, heterogeneous three dimensional stack. We show that a high-order surface-plasmon-polariton transverse mode mediates efficient coupling between the InAs/GaAs quantum dots and the plasmonic cavity, paving the way for developing plasmonic quantum light …
A single quantum dot deterministically coupled to a photonic crystal environment constitutes an indispensable elementary unit to both generate and manipulate single-photons in next-generation quantum photonic circuits. To date, the scaling of the number of these quantum nodes on a fully-integrated chip has been prevented by the use of optical pumping strategies that require a bulky off-chip laser along with the lack of methods to control the energies of nano-cavities and emitters. Here, we concurrently overcome these limitations by demonstrating electrical injection of single excitonic lines w…
Integration of optical elements into scalable chips has been at the center of a large effort in recent years. Concurrently, the separation between the diverse functions, namely switches, detectors or emitters increases significantly the final number of components on chip. Such technical limitations may be overcome by introducing agile devices able, for example, to simultaneously detect, process and emit a coherent signal. Such a pathway has been explored with different approaches that bear advantages and drawbacks. Polaritons have often been proposed as promising candidates for multifunctional…
An important building block for on-chip photonic applications is a scaled emitter. Whispering gallery mode cavities based on III-Vs on Si allow for small device footprints and lasing with low thresholds. However, multimodal emission and wavelength stability over a wider range of temperature can be challenging. Here, we explore the use of Au nanorods on InP whispering gallery mode lasers on Si for single mode emission. We show that by proper choice of the antenna size and positioning, we can suppress the side-modes of a cavity and achieve single mode emission over a wide excitation range. We es…
We investigate correlations between orthogonally polarized cavity modes of a bimodal micropillar laser with a single layer of self-assembled quantum dots in the active region. While one emission mode of the microlaser demonstrates a characteristic s-shaped input-output curve, the output intensity of the second mode saturates and even decreases with increasing injection current above threshold. Measuring the photon auto-correlation function g^{(2)}(τ) of the light emission confirms the onset of lasing in the first mode with g^{(2)}(0) approaching unity above threshold. In contrast, strong photo…
Semiconductor nanocrystals can be synthesized using inexpensive, scalable, solution-based techniques, and their utility as tunable light emitters has been demonstrated in various applications, including biolabeling and light-emitting devices. By contrast, the use of colloidal nanocrystals for optical amplification and lasing has been limited by the high input power densities that have been required. In this work, we show that colloidal nanoplatelets (NPLs) produce amplified spontaneous emission (ASE) with pump-fluence thresholds as low 6 uJ/cm2 and gain as high as 600 cm-1, both a 4-fold impro…
Local control of the generation and interaction of indistinguishable single photons is a key requirement for photonic quantum networks. Waveguide-based architectures, in which embedded quantum emitters act as both highly coherent single photon sources and as nonlinear elements to mediate photon-photon interactions, offer a scalable route to such networks. However, local electrical control of a quantum optical nonlinearity has yet to be demonstrated in a waveguide geometry. Here, we demonstrate local electrical tuning and switching of single photon generation and nonlinear interaction by embedd…
Simultaneous anti-bunched and super-bunched photons from a GaAs Quantum dot in a dielectric metasurface
Sandia National Laboratories（桑迪亚国家实验室）；Center for Integrated Nanotechnologies, Sandia National Lab（桑迪亚国家实验室集成纳米技术中心）；University College London（伦敦大学学院）；Department of Electrical and Computer Engineering, University of Oklahoma（俄克拉荷马大学电气与计算机工程系）；Center for High Technology Materials, University of New Mexico（新墨西哥大学高技术材料中心）
High-bit-rate nanocavity-based single photon sources in the 1,550-nm telecom band are challenges facing the development of fibre-based long-haul quantum communication networks. Here we report a very fast single photon source in the 1,550-nm telecom band, which is achieved by a large Purcell enhancement that results from the coupling of a single InAs quantum dot and an InP photonic crystal nanocavity. At a resonance, the spontaneous emission rate was enhanced by a factor of 5 resulting a record fast emission lifetime of 0.2 ns at 1,550 nm. We also demonstrate that this emission exhibits an enha…
