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We investigate the emission of waves by a thin silver nanostrip placed into the center of a circular quantum wire (QWR), in the visible-light range. Our analysis uses the mathematically grounded approach called lasing eigenvalue problem (LEP). Keeping in mind that at the threshold the lasing-mode frequency is real valued (does not attenuate in time), the LEP is formulated as a boundary-value problem for the Maxwell equations with exact boundary conditions and the Sommerfeld radiation condition. The eigenvalues are pairs of real numbers, where the first is the emission wavelength and the second is the associated threshold value of material gain in the QWR. Due to the twofold symmetry of the cross-sectional geometry, we split the studied problem into four different independent classes of symmetry and derive four symmetry-adapted Green's functions of the QWR without strip. On imposing the generalized boundary conditions and taking into account these Green's functions, we obtain four independent integral equations (IEs) at strip's median line. We discretize these IEs with the Nystrom-type schemes and further look for the eigenvalues of each class separately with the aid of iterative search algorithm. Our analysis shows that such a plasmonic-strip-based nanolaser can emit visible light on the localized surface plasmon modes and also on the shell modes or QWR polariton modes perturbed by the strip. Single-mode operation is apparently possible provided that the QWR diameter is small, and hence, the first shell mode is blue-shifted.

Surface plasmon polariton (SPP) nanolasers have recently emerged as promising candidates for generating a coherent light source in nanophotonic integration circuits. The properties of SPP nanolasers, such as group velocity, mode area, modulation speed, and threshold performance, can be manipulated using a dispersion relation. In this study, we investigated the characteristics of SPP nanolasers operated near and far from the SP frequency. Our results indicated that SPP nanolaser performance can be significantly influenced by manipulating the dispersion relation.

Semiconductor surface plasmon polariton (SPP) waveguide has unique optical properties and compatibility with existing integrated circuit manufacturing technology; thus, SPP devices of semiconductor materials have wide application potential. In this study, a new integrated graphene SPP waveguide is designed using the bottom and top roles of graphene. Moreover, a T waveguide structure is designed by InGaAs of semiconductor gain, with rectangular GaAs material on both sides. The structure adopts light to stimulate the SPP, where its local area is enhanced by the interaction between two interface layers and a semiconductor gain and where its frequency can be adjusted by the thickness of the graphene. Characteristic analysis reveals the coupling between the T semiconductor gain and the SPP mode. The propagation distance of the waveguide can reach 75 cm, the effective mode field is approximately 0.0951λ 2, the minimum of gain threshold is approximately 2992.7 cm−1, and the quality factor (FOM) can reach 180. The waveguide structure which provides stronger localization can be compatible with several optical and electronic nanoscale components. That means, it can provide light for surface plasmon circuit and also can provide a great development in the low-threshold nanolaser.

We theoretically demonstrate the generation and radiation of coherent nanoplasmons powered by a single three-level quantum emitter on a plasmonic nanoresonator. By pumping the three-level emitter in a Raman configuration, we show a pathway to achieve macroscopic accumulation of nanoplasmons due to stimulated emission in the nanoresonator despite their fast relaxation. Thanks to the antenna effect of the nanoresonator, the system acts as an efficient and bright nanoscopic coherent light source with a photon emission rate of hundreds of Terahertz and could be realized with solid-state emitters at room temperatures in pulse mode. We provide physical interpretations of the results and discuss their realization and implications for ultra-compact integration of optoelectronics., Comment: 15 pages, 7 figures

The recent development of plasmonics has break through the optical diffraction limit and realized ultracompact nanolasers that can directly generate coherent optical fields at the nanometre scale. However, it remains to a profound understanding on the light and matter interactions in so-called Spaser, especially on the coupling mechanism between the surface plasmon and exciton although many reports have claimed surface plasmonic lasers. Here, we demonstrated a ZnO/SiO2/Ag structural hybrid plasmonic nanolaser and compared with a conventional photonic laser systematically. We proposed that these two kinds of lasers originated from the entirely different optical gain mechanisms, and resulted in the generation of lasing mode shift. Time-resolved spectra collected from these two samples at room temperature presented the dynamic process of exciton recombination and revealed the energy-transfer from excitons to SPs. Our research provides an important theoretical and experimental basis for the practical applicat...

We propose and demonstrate a direct integration of a wavelength-scale III–V nanolaser onto a silicon-on-insulator (SOI) waveguide. By employing high-precision microtransfer printing techniques, with an optimally designed photonic crystal nanolaser structure, we experimentally achieved a coupling efficiency of 83% between the InGaAsP nanobeam laser and the SOI waveguide. Our III–V nanobeam laser is designed as an asymmetric one-dimensional photonic crystal cavity, which allows unidirectional coupling to the combined III–V nanobeam waveguide with high efficiency. Through the compact vertical coupler in the region where the III–V and SOI waveguides overlap at the optimal length of 3.2 μm, 88% of the light from the printed III–V nanolaser can theoretically be coupled to a vertically integrated SOI waveguide.

Perovskite nanocrystals open up a bright future for nanolasers, for their various instinct advantages (such as large absorption cross section and optical gain, high fluorescence quantum yields, etc.) can greatly benefit the design and fabrication of nanolasers with a low threshold, high emission efficiency, and good integration. Although numerous investigation efforts have been devoted to exploring the perovskite nanolaser of the single-photon-pumped type, the study of up-conversion lasing excited by two-photon-pumping is still established on the structures of micrometer scale with multiple mode, which is not in favor of improving the working stability and scale miniaturization of future nanolasers. To expand the application of the perovskite nanocrystal in nanolasers, we studied the perovskite (CsPbX3, X = Cl, Br) nanoplates fabricated by the supersaturated recrystallization approach and observed single mode up-conversion lasing from a single nanoplate with a low threshold of 4.84 μJ/cm2. In addition, th...

By exploiting one-dimensional photonic crystal nanocavities, an ultra-compact indium phosphide-on-silicon laser diode with low current threshold, high wall-plug efficiency and high integrability is demonstrated. The most-awaited convergence of microelectronics and photonics promises to bring about a revolution for on-chip data communications and processing1. Among all the optoelectronic devices to be developed, power-efficient nanolaser diodes able to be integrated densely with silicon photonics and electronics are essential to convert electrical data into the optical domain. Here, we report a demonstration of ultracompact laser diodes based on one-dimensional (1D) photonic crystal (PhC) nanocavities2,3,4 made in InP nanoribs heterogeneously integrated on a silicon-waveguide circuitry. The specific nanorib design enables an efficient electrical injection of carriers in the nanocavity without spoiling its optical properties. Room-temperature continuous-wave (CW) single-mode operation is obtained with a low current threshold of 100 µA. Laser emission at 1.56 µm in the silicon waveguides is obtained with wall-plug efficiencies greater than 10%. This result opens up exciting avenues for constructing optical networks at the submillimetre scale for on-chip interconnects and signal processing.

Objectives: Surface plasmon exhibited in nano-sized particles such as gold, silver, copper has recently attracted a great deal of attention due to the enhancement and tunable optical properties in the visible to near-infrared region of the electromagnetic spectrum. In this work, the optical properties of dielectric material at noble metal core-shell nanoparticles were investigated. Methods: Mie theory is the analytical method is used to study via parameters of extinction, scattering and absorption efficiencies. The samples for studying were the composites of a dielectric material core coated by a thin noble metal (Ag, Au, and Cu). The core size was fixed at 50 nm, while the metal shell thicknesses were varied from 3 nm to 40 nm. Findings: The calculated optical properties were found that the surface plasmon resonance can be enhanced and tuned the wavelength from the near ultraviolettonear infrared regions by varying the shell thickness. Application: The dielectric core coated with a thin noble metal to promote the properties of the core can be applied in the field of plasmonic nanolaser, nonlinear plasmonic antenna, light trapping in thin-film organic solar cells, and biomedical research.

It has been a long-term dream to achieve nanolaser array with uniform laser wavelengths, high densities, and high output powers. However, such kind of nanolaser array is practically quite challenging due to the variations of both bottom-up synthesized nanostructures and top-down etched devices. Herein we explore a simple method to achieve such kind of uniform nanolaser array. By placing a single crystalline CH3NH3PbBr3 nanoribbon onto a gold grating, both of our numerical calculation and experimental results show that the light can be well trapped by a waveguide mode around the air slot area, providing the possibility of high power nanolaser in a narrow air slot. The smallest size of the gap for light confinement is optimized to around 350–400 nm. Consequently, a high-density, uniform nanolaser array has been experimentally realized. And the coupling between different subunits is found to be negligibly small. We believe that this research can boost the progresses of nanolaser array and the corresponding p...

Well understanding the interfacial carrier dynamics in semiconductor axial nanowire (NW) heterostructures is crucial important for the performance optimization of integrated photonics and optoelectronics devices. However, the growth of high-quality semiconductor axial NW heterostructures still remains a great challenge. Here, we develop a source switching vapor growth route and demonstrate the successful growth of CdS-CdSSe-CdS axial NW heterostructures with highly crystallized and composition sharp interface, which acts as the model material for the study of interfacial carrier dynamics. Under femtosecond laser pumping, the achieved NW heterostructures can simultaneously give lasing at the green (~516.4 nm) and red (~597.9 nm) spectral regions, demonstrating the well radial confinement of the both color emitted light. Time-resolved photoluminescence (PL) measurements reveal the energy transfer (ET) from the CdS to the CdSSe segments corresponds to the interaction of the guided green light with CdSSe at the hetero-interfaces, which makes the CdSSe segment have higher carrier density and emission efficiency, resulting in the more obvious power induced blueshift and lower lasing threshold comparing with the green emission. These obtained CdS-CdSSe-CdS axial NW heterostructures with effective ET have the potential applications in high performance optical and optoelectronic nanoscaled devices, like nanolaser, photodetectors, waveguide etc.

Here we report the successful demonstration of lasing oscillation in a subwavelength semiconductor nanowire (100 nm in diameter) at telecom wavelengths. Although a subwavelength nanowire is too thin to configure an efficient optical cavity by itself, we have combined the nanowire with a Si photonic crystal to form a nanowire-induced hybrid nanocavity. This unique configuration enables us to realize an efficient nanowire-based nanolaser on a Si platform. Our systematic study, which included L–L characteristics, emission wavelength, emission line width, emission lifetime, and photon correlation, has unambiguously revealed the lasing operation of the nanowire at 4 K. In addition, we have succeeded in changing the laser oscillation wavelength by moving the nanowire through a trench in the photonic crystal, which reveals the unique feature of this hybrid nanocavity. This is the first demonstration of telecom band subwavelength nanowire lasers, which may also be important for Si photonics applications.

Next-generation optoelectronic devices and photonic circuitry will have to incorporate on-chip compatible nanolaser sources. Semiconductor nanowire lasers have emerged as strong candidates for integrated systems with applications ranging from ultrasensitive sensing, to data communication technologies. Despite significant advances in their fundamental aspects, the integration within scalable photonic circuitry remains challenging. Here we report on the realization of hybrid photonic devices consisting of nanowire lasers integrated with wafer-scale lithographically designed V-groove plasmonic waveguides. We present experimental evidence of the lasing emission and coupling into the propagating modes of the V-grooves, enabling on-chip routing of coherent and sub-diffraction confined light with room temperature operation. Theoretical considerations suggest that the observed lasing is enabled by a waveguide hybrid photonic-plasmonic mode. This work represents a major advance towards the realization of application-oriented photonic circuits with integrated nanolaser sources., 24 pages, 4 figures

Lead halide perovskites are widely applied in not only photovoltaics, but also on-chip light source, nanolaser, and photon detection. In order to promote the incorporation of perovskite into integrated devices, microscale color patterning flexibility is a very important step. Femtosecond (fs) laser fabrication has shown significant advantages of high spatial resolution, low surround damage, and high processing efficiency over the other laser fabrication. Compared to the state-of-art techniques, the straightforward fs-direct laser writing (fs-DLW) also has advantages of mask-free, simple one step, and contactless. Here, a specially designed formamidinium lead mixed-halide nanoplatelet (FAPb(BrxI1-x)3 NP) with gradient bandgap is fabricated by chemical vapor deposition method. Then, spatially resolved modulation of the fluorescence by fs-DLW is demonstrated on the as-grown NP. The fluorescence color is modulated from red to green under a controlled laser pulse, due to the replacement of iodide ions by bromide ions. Specifically, the as-grown NP (thickness≈800 nm) is with a gradual bromide-iodide composition along the depth, mainly exhibits an emission of 710-nm from the bottom iodine rich phase. After halide substitution induced by fs-DLW, new fluorescence peaks appear in the wavelength range of 540 to 700 nm, which is controlled by the fs-DLW conditions. The fluorescent color is spatially modulated from red to green, enabling microscale resolved multicolor emission, implying the potential applications in micro-encryption, sensors, multicolor displays, lasers, and light-emitting devices.

ZnO nanocavities have advantage to working as optoelectrical nanodevices integrated on chip at high temperature owing to high exciton binding energy. In this work, a single inverted hexagonal ZnO pyramid (HZOP) nanolaser is fabricated successfully by reducing the defect with chemical vapor deposition (CVD). The optical leakage of HZOP is conquered by the inverted configuration to increase the refractive index contrast between ZnO pyramid and surrounding media. Helical whispering-gallery-like mode is proposed to dominate the lasing of HZOP nanolaser. All of the lasing peaks are found to exist at wavelength longer to the fluorescence emission of ZnO, which is ascribed to the large loss represented by the large imaginary part of ZnO refractive index at shorter wavelength. The threshold and linewidth are measured to be 5.27 mJ/cm2 and 0.27 nm, respectively. HZOP nanolaser is a new ultraviolet coherent light source to be integrated on chip at room temperature or higher temperature.

International audience; Mode locking is predicted in a nanolaser cavity forming an effective photonic harmonic potential. The cavity is substantially more compact than a Fabry-Perot resonator with a comparable pulsing period, which is here controlled by the potential. In the limit of instantaneous gain and absorption saturation, mode locking corresponds to a stable dissipative soliton, which is very well approximated by the coherent state of a quantum mechanical harmonic oscillator. This property is robust against noninstantaneous material response and nonzero phase-intensity coupling.

In recent years, extensive efforts have been made for design and fabrication of low threshold spasers or plasmonic nanolasers at a deep subwavelength scale. Plasmonic nanolasers with coupled-nanorods structure can realize this purpose due to energy concentration in nano size volumes and effective amplification mechanisms. In this study, a group of structures based on metallic and CdS coupled nanorods are designed and analyzed using the finite element method (FEM). By changing the lateral adjacent surfaces of the metal and semiconductor nanorods through utilizing regular polygons as the cross sections of the nanorods, different characteristics of the plasmonic nanolaser are investigated. Simulation results show that the mode area normalized by the diffraction limit area is as low as 0.0062 in the structures based on hexagonal metallic core with circular semiconductor nanorods while structures based on circular Ag core with hexagonal CdS nanorods can provide a low threshold gain as 1.310 μm-1. Also, it is shown that if ZnO be used as the semiconductor gain material instead of CdS, a normalized mode area of almost one tenth can be attained in a structure with dodecagonal metallic core and circular ZnO nanorods.

In this work, we experimentally study the carrier and refractive index dynamics of InGaAs nanopillar grown on a Si on insulator (SOI) substrate. The recombination process of the InGaAs NP is characterized with different optical techniques. Temperature dependent photoluminescence (PL) at 0.5mW excitation power is carried out to determine the influence of temperature on carrier dynamics. The radiative recombination lifetime has been studied at 7K from time-resolved photoluminescence (TRPL) experiments at a certain excitation power. The optimal combination of pitch (separation between NPs) and diameter in the growth process of this nanostructure has also been measured. These results will contribute to further optimization of the InGaAs nanolaser for integration of III-V optoelectronics on SOI substrates.

A nanolaser using AlGaAs nanodisk is theoretically demonstrated based on anapole state. The radius and height of the nanodisk are optimized to be 240nm and 120nm through geometry tuning based on Mie scattering theory. We have achieved near-field lasing at 1017nm with linewidth around 3.5nm.

Rubidium lead halides (RbPbX3 ), an important class of all-inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t≈0.78, all-inorganic RbPbBr3 has not been reported. Now, the crystal structure, X-ray diffraction (XRD) pattern, and band structure of perovskite-phase RbPbBr3 has now been investigated. Perovskite-phase RbPbBr3 is unstable at room temperature and transforms to photoluminescence (PL)-inactive non-perovskite. The structural evolution and mechanism of the perovskite-non-perovskite phase transition were clarified in RbPbBr3 . Experimentally, perovskite-phase RbPbBr3 was realized through a dual-source chemical vapor deposition and annealing process. These perovskite-phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475-540 nm) single-mode lasing with a high Q of about 2100.

We experimentally demonstrate the lasing action of a new nanolaser design with a tunnel junction. By using a heavily doped tunnel junction for hole injection, we can replace the p-type contact material of a conventional nanolaser diode with a low-resistance n-type contact layer. This leads to a significant reduction of the device resistance and lowers the threshold voltage from 5 V to around 0.95 V at 77 K. The lasing behavior is verified by the light output versus the injection current (L-I) characterization and second-order coherence function measurements. Because of less Joule heating during current injection, the nanolaser can be operated at temperatures as high as 180 K under CW pumping. The incorporation of heavily doped tunnel junctions may pave the way for other nanoscale cavity design for improved heat management.

Lasing in organic media with very low gain has been pursued for a long time in optoelectronics. Here, we experimentally demonstrate that plasmonic lasing in the visible regime at room temperature can be achieved by hybridizing active media of very low optical gain such as ionic liquid and polymethylmethacrylate with three-dimensional (3D) plasmonic metamaterials. The 3D nanostructure consists of a double-layer N-shaped silver wire-hole array with strongly coupled multiple hot spots densely packed in each unit cell. These hot spots overlap perfectly with the gain media, allowing efficient gain-plasmon coupling in subwavelength volumes. The periodic arrangement of hot spots, as the metal and dielectric are distributed in an alternate manner along both transverse and vertical directions, results in ultrastrong suppression of scattering losses. In addition, the lasing characteristics, including threshold, intensity and polarization can be controlled by the lattice constant and geometry of metamaterials. Such a plasmonic nanolaser proves to be of low threshold and low gain requirement, providing an essential step towards easy-processing organic based optoelectronics. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Graphene is a two-dimensional (2D) structure that creates a linear relationship between energy and momentum that not only forms massless Dirac fermions with extremely high group velocity but also exhibits a broadband transmission from 300 to 2500 nm that can be applied to many optoelectronic applications, such as solar cells, light-emitting devices, touchscreens, ultrafast photodetectors, and lasers. Although the plasmonic resonance of graphene occurs in the terahertz band, graphene can be combined with a noble metal to provide a versatile platform for supporting surface plasmon waves. In this study, we propose a hybrid graphene-insulator-metal (GIM) structure that can modulate the surface plasmon polariton (SPP) dispersion characteristics and thus influence the performance of plasmonic nanolasers. Compared with values obtained when graphene is not used on an Al template, the propagation length of SPP waves can be increased 2-fold, and the threshold of nanolasers is reduced by 50% when graphene is incorporated on the template. The GIM structure can be further applied in the future to realize electrical control or electrical injection of plasmonic devices through graphene.

Ultra-small and efficient laser sources is an emerging technology for realizing optical on-chip interconnects [1]. A line defect cavity formed by omitting a number of holes in a photonic crystal membrane with embedded quantum dot or quantum well gain material shows promise as a candidate for realizing lasers with small mode volumes and low threshold powers, while allowing direct modulation at several gigabits per second [2]. Further, the slow-light phenomena occurring in passive line defect photonic crystal waveguides results in enhanced gain [3]. As such the gain material is a key component of the nanolaser. For good thermal operation of the nanolaser the gain material is embedded in an InP membrane [4] which in turn makes optical characterization of the gain material difficult.

Spontaneous photon bursts are observed in the output collected from a mesoscale semiconductor-based laser near the lasing threshold. Their appearence is compared to predictions obtained from Laser Rate Equations and from a Stochastic Laser Simulator. While the latter is capable of predicting the observed large photon bursts, the photon numbers computed by the former produces a noisy trace well below the experimentally detectable limit. We explain the discrepancy between the two approaches on the basis of an incorrect accounting of the onset of stimulated emission by the Rate Equations, which instead are capable of complementing the physical description through topological considerations., 12 pages, 7 figures, 76 references

A measurement method that can be used to extract the relative intensity noise of a nanolaser is introduced and analyzed. The method is based on optical injection of emission from a nanolaser, serving as a master oscillator, transferring its intensity fluctuations to a low-noise semiconductor laser serving as a slave oscillator. Using the stochastic rate equation formalism, we demonstrate that the total relative intensity noise of the system is a weighted superposition of the relative intensity noise of individual lasers. We further discuss the analytical relations that can be used to extract the relative intensity noise spectrum of a nanolaser. Finally, we use mutual correlation as a mathematical tool to quantify the degree of resemblance between the injected and extracted intensity fluctuations, theoretically confirming that the spectra are at least 97% correlated within the 3-dB bandwidth when an injection strength is chosen properly.

Here we experimentally characterize photonic crystal nanolasers where the first endhole of the mirror has been systamatically shifted. FDTD simulations of similar passive cavities are done in order to find the expected evolution of the quality factor. We find that the predicted increase in the quality factor of the equivalent passive cavities leads to a decrease in the threshold power of the active nanolasers as expected. The maximum output power for varying endhole shifts has also been investigated and shifting the holes to optimize quality factor leads to lower maximum output power, when measuring from the top. The mirror of the photonic crystal cavity is further investigated as the mirror phase and penetration depth into the mirror are determined as a function of the endhole shift.

International audience

Dielectric nanoantennas and metasurfaces have recently emerged as a new nanophotonic platform complimenting conventional plasmonics for light control at the nanoscale [1]. Due to their low losses, wide range of available electric and magnetic resonances and compatibility with conventional nanofabrication processes they provide a unique toolkit to achieve new functionalities and build highly-efficient nanophotonic devices. So far however, most of the demonstrated functionalities have been limited to passive light control while emission properties of the nanoantennas have rarely been studied. In this talk, I will review our recent research in the direction of light emitting semiconductor nanoantennas and metasurfaces. In particular I will show our first experimental demonstration of lasing action in active semiconductor 2D nanoantenna arrays based on bound state in the continuum [2]. I will also show how lasing can be achieved in 1D nanoantenna chains and even single nanoantennas using interference effects between different resonant modes. These results expand the toolkit of dielectric nanoantennas towards active functionalities providing a new platform for making chip-scale directional laser devices. References: 1) A. I. Kuznetsov et al., “Optically resonant dielectric nanostructures”, Science 354, aag2472 (2016); 2) S. T. Ha et al., “Directional lasing in resonant semiconductor nanoantenna arrays”, Nature Nanotech. (2018), in press.

In this work, we present the model of plasmonic chrial nanolasers composed of aluminum-coated gallium-nitride (GaN) gammadions, which may lase with a high degree of circular polarization at room temperatures. Using the finite-element method, we examine resonant modes of the four-fold rotationally symmetric cavities of gammadions whose resonant frequencies lie in the gain spectrum of GaN. We find a degenerate doublet of resonant modes which can couple to plane waves in the far-field zone above gammadions. Their near-field profiles exhibit localized distribution in the arms of gammadions and a Fabry-Perot standing-wave pattern along the post. In practice, fabrication imperfections would inevitably spoil the four-fold rotation symmetry of gammadions. Typical perturbation could lift the degeneracy of doublet and leads to mixing of the two degenerate modes which may still output signals with observable handedness above gammadions. Considering a gammadion cavity with a single elongated arm, we show that the magnitude of dissymmetry factor of its resonant mode can be larger than unity. Our calculations are consistent with the experimental results, indicating that the right-handed gammadion cavities lase with a magnitude of dissymmetry factors near 1 at a wavelength of 364 nm. The dimensionless effective mode volume scaled by the cube of effective wavelength is 2.62, reflecting a modal distribution remarkably confined in the plasmonic structures and the capability of enhancing the spontaneous-emission rate noticeably. These chiral nanolasers with an ultrasmall footprint could be potentially utilized as future circularly-polarized photon source at the chip level.

We introduce a model describing a photonic crystal III-V/Silicon nanolaser composed of two sections. We predict an excitable dynamics mimicking a neuron-like response. This technology is scalable and amenable to massive integration.

В работе теоретически исследуется модель лазера на двух атомах. Оба двухуровневых атома находятся в условиях некогерентной накачки, помещены в резонатор Фабри – Перо и взаимодействуют с выделенной затухающей модой. В случае выключенного поля накачки рассматривается влияние межатомного диполь-дипольного взаимодействия на эволюцию затухающей моды резонатора. Показано, что эта эволюция существенно зависит от начального суперпозиционного состояния атомов. При включенной некогерентной накачке «память» о начальном состоянии атомов в резонаторе со временем исчезает., In the paper, the simple model of а two-atom laser is theoretically studied. The both dipole-dipole coupled atoms are under conditions of incoherent pump, are placed into the Fabry – Perot cavity and interact with a single damping field mode. In the switched-off pump position, the effect of dipole-dipole interaction on evolution of the damping mode has been considered. This evolution was shown to be strongly dependent on an initial atomic superposition state of atoms. In the switched-on pump position, the ‘memory’ for the initial atomic state should collapse with time.

We report the single-mode, high-quality, picosecond pulses laser from an individual subwavelength scaled perovskite nanocuboid. The upconverted lasing threshold is as low as 374 μJ/cm2 with temperature-insensitive optical gain and high characteristic temperature.

The luminescence and inner structure of GaAs-AlGaAs quantum well tube (QWT) nanowires were studied using low-temperature cathodoluminescence (CL) spectroscopic imaging, in combination with scanning transmission electron microscopy (STEM) tomography, allowing for the first time a robust correlation between the luminescence properties of these nanowires and their size and inner 3D structure down to the nanoscale. Besides the core luminescence and minor defects-related contributions, each nanowire showed one or more QWT peaks associated with nanowire regions of different diameters. The values of the GaAs shell thickness corresponding to each QWT peak were then determined from the nanowire diameters by employing a multishell growth model upon validation against experimental data (core diameter and GaAs and AlGaAs shell thickness) obtained from the analysis of the 3D reconstructed STEM tomogram of a GaAs-AlGaAs QWT nanowire. We found that QWT peak energies as a function of thus-estimated (3–7 nm) GaAs shell thickness are 40–120 meV below the theoretical values of exciton recombination for uniform QWTs symmetrically wrapped around a central core. However, the analysis of the 3D tomogram further evidenced azimuthal asymmetries as well as (azimuthal and axial) random fluctuations of the GaAs shell thickness, suggesting that the red-shift of QWT emissions is prominently due to carrier localization. The CL mapping of QWT emission intensities along the nanowire axis allowed to directly image the nanoscale localization of the emission, supporting the above picture. Our findings contribute to a deeper understanding of the luminescence-structure relationship in QWT nanowires and will foster their applications as efficient nanolaser sources for future monolithic integration onto silicon.

In this work, we study the lasing conditions of the transverse electric (TE) modes of micro- and nanotubes coated internally with a thin metallic layer. This geometry may tackle some of the problems of nanolasers and spasers as it allows the recycling of the active medium while providing a tunable plasmonic cavity. The system presents two types of TE modes: cavity modes (CMs) and whispering-gallery modes (WGMs). On the one hand, we show that the lasing of WGM is only possible in nanoscale tubes. On the other hand, for tubes of some micrometers of diameter, we found that the system presents a large number of CMs with lasing frequencies within the visible and near-infrared spectrum and very low gain thresholds. Moreover, the lasing frequencies of CMs can be accurately described by a simple one-parameter model. Our results may be useful in the design of micro- and nanolasers for `lab-on-chip' devices, ultra-dense data storage, nanolithography, or sensing., Comment: The Journal of Physical Chemistry C (2019)

Radiation is a very important energy conversion process in engineering optics. Effective thermal radiation management can not only improve the efficiency of thermophotovoltaics but also realize passive radiative cooling, thermal cloak, and camouflage. Besides, light-emitting diode (LED) with small volume and high efficiency is poised to replace the traditional light bulb and liquid crystal display (LCD) in the next few decades. In addition, minimized micro-/nanolaser that can serve as coherent light sources in on-chip electro-photonic circuits can be widely applied in nanoscale applications. Finally, if the phase retardation of coherent emitters can be actively controlled in a compact manner, high-performance optical phased light detection and ranging will replace the traditional beam scanning technology based on mechanical steering. In this chapter, we give a detailed discussion about the radiation engineering technology and optical phased array.

We report on our initial attempt to characterize the intrinsic frequency response of metal-clad nanolasers. The probed nanolaser is optically biased and modulated, allowing the emitted signal to be detected using a high-speed photodiode at each modulation frequency. Based on this technique, the prospect of high-speed operation of nanolasers is evaluated by measuring the D-factor, which is the ratio of the resonance frequency to the square root of its output power (fR/P_out^2). Our measurements show that for nanolasers, this factor is an order of magnitude greater than that of other state-of-the-art directly modulated semiconductor lasers. The theoretical analysis, based on the rate equation model and finite element method simulations of the cavity is in full agreement with the measurement results., Comment: Optics Express

Nonlinear dynamics of semiconductor nanolasers subjected to distributed feedbacks from fiber Bragg grating (FBG) are investigated through modified rate equations, which include the unique Purcell cavity-enhanced spontaneous emission factor F and spontaneous emission coupling factor β. In the analysis, the effects of F, β, frequency detuning, feedback strength, feedback delay, FBG bandwidth and length on chaotic performance are evaluated. It is observed that the approach of FBG feedback outperforms mirror feedback in terms of concealing time-delay signature and increasing effective bandwidth by choosing intermediate feedback strength and frequency detuning. Additionally, chaotic regions and the corresponding chaotic characteristics are revealed by dynamical mappings of nanolasers subjected to FBG feedback. The results show that decreased F, β and increased FBG bandwidth can extend the parameter range of chaos. However, the variation of feedback delay and FBG length has no obvious effect on TDS suppression and effective bandwidth enhancement. Most importantly, high quality optical chaos with low TDS and high effective bandwidth induced by increased dispersion is obtained within broad parameter regions considered, which is beneficial to achieving chaos-based applications.

On-chip coherent light source has always been fascinating and intriguing due to its various potential applications. In the past decades, there has been some progress in the development of chip coherent light (e.g., nanolaser, Bose-Einstein condensation and nonlinear optical effects). However, these methods strictly depend on materials and extreme experimental conditions, and are usually not tunable. Here, a hybrid structure is designed which combines a chirped surface plasmon metasurface with a monolayer transition metal dichalcogenide (TMDC) to achieve a coherent second harmonic generation (SHG) covering the entire visible light spectrum. Using only finite number of metallic grooves, a continuous resonance tuning is obtained. By translating the metasurface in space, a space-frequency locking SHG is demonstrated. Although the Q factor of the surface plasmon cavity is low, its near-field enhancements of both fundamental and SH waves are still obvious. Significantly, the broad linewidth of plasmonic cavity leads to a large degree of overlap between adjacent localized modes, that enables the tuning of the output wavelength continuously at room temperature. Meanwhile, the exciton resonance also plays an important role. This monolithic tunable device demonstrates the potentials of 2D material-plasmon hybrid metasurface and to construct an efficient broadband tunable on-chip coherent light source.

Plasmonic nanoresonators consisting of a gold nanorod and a spherical silica-core and gold-shell, both coated by a gain layer, were optimized to maximize the near-field enhancement (NF-type) and far-field outcoupling (FF-type), and to enter into the spasing operation region (NF-c*-type). It was shown that in case of moderate concentration the nanorod has more advantages: smaller lasing threshold, larger slope efficiency and achieved intensities in the near-field, in addition in FF-type system smaller gain and outflow threshold, earlier flipping and larger far-field out-coupling efficiency. However, the near-field (far-field) bandwidth is smaller in for NF-type (FF-type) core-shell nanoresonators. In case of larger concentration although the slope efficiency and near-field intensity remain larger and the far-field redistribution is more efficient in case of the nanorod, the core-shell nanoresonator is more advantageous, taking into account the smaller lasing, outflow, absorption and extinction cross-section thresholds, as well as the larger internal and external quantum efficiencies. In addition to this the bandwidth of core-shell nanoresonator is also smaller. It was also shown that the strong-coupling of time-competing plasmonic modes accompanies the transition from lasing to spasing., 17 pages, 4 figures

Plasmonic nanolasers (PNLs) have attracted much attention in recent years due to their light-trapping capabilities beyond the diffraction limit. However, the physics that underpins the lasing action in such devices has not received sufficient treatment in the literature. The contribution of plasmons in PNLs needs to be understood at a granular level for designing enhanced nanoscopic lasers. In this work, we present a modal decomposition-based analysis of a planar PNL that employs a two-dimensional metallic nanohole array interfaced with the gain medium. Using state-of-the-art simulation techniques, we isolate the plasmonic mode that emerges at the metal–gain medium interface interlaced with scattering modes. We present a step-by-step dispersion analysis to identify the possible modes supported by the planar PNL structure and locate the operating point of the PNL. Furthermore, we show how the plasmonic mode regulates the lasing action, and hence, can serve as a tool for laser tunability.