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The metallic cavity has been recognized as the promising structure to realize the subwavelength nanolasers with the dimensions of mode volumes considerably smaller than the optical diffraction limit. However, the current nanolasers based on metallic cavity are realized in near-infrared ranges, since the high optical loss from metal makes the metallic lasing at the visible wavelength challenging. Here, we propose an innovative approach to fabricate metallic cavity plasmonic nanolaser based on Au-coated perovskite nanowires synthesized by an in situ solution method. The intrinsic ohmic loss of metal could be overcome by the high gain of the perovskite. The laser presents a prominent lasing behavior in the visible range at 548 nm. The mode area is reduced to λ2/48, the Purcell factor reaches up to 108, and the physical dimension is only 150 nm. To be noted, the competition between plasmonic modes and photonic modes was observed for the first time in the metallic cavity nanolasers. This work promotes the application of perovskite composite nanostructures to photonic devices.

Summary The remarkable photophysical properties of halide perovskites have led to high-performance lasers. The slow emission dynamics and diffraction-limited device, however, impose an intrinsic barrier on realizing ultrafast and compact lasers for integrated optoelectronic applications. Plasmonic cavities have been employed to reduce laser size. Yet the emission dynamics is fundamentally limited due to the dilemma between ever-reduced cavity size and the increase of losses. Here, we show a subwavelength-scale lasing perovskite with ultrahigh Purcell enhancement of 209 that greatly enhances emission dynamics under ambient conditions. The hybrid surface plasmon polaritons (SPPs) coupled with perovskites significantly reduce plasmonic and trap state loss channels and promote a strong Purcell effect. Moreover, the realization of SPPs confinement away from the perovskite region mitigates gain degradations that enables superior long-term device stability and reliability. Our study opens a new avenue for on-chip ultrafast optoelectronics and fundamental studies of light-matter interactions at the strongly confined field.

We study active dielectric metasurfaces composed of two-dimensional arrays of split-nanodisk resonators fabricated in InGaAsP membranes with embedded quantum wells. Depending on the geometric parameters, such split-nanodisk resonators can operate in the optical anapole regime originating from an overlap of the electric dipole and toroidal dipole Mie-resonant optical modes, thus supporting strongly localized fields and high-Q resonances. We demonstrate room-temperature lasing from the anapole lattices of engineered active metasurfaces with low threshold and high coherence.

This essay is my reminiscences of many interesting discussions I had with Mark Stockman over the years, mostly around the spaser, its meaning, and its relationship with plasmonic nanolasers.

Based on the discrete sources method, a mathematical model of the plasmon nanolaser resonator deposited on the prism surface in an active ambient medium is developed and implemented, which allows taking into account the non-local effect (NLE) in the plasmon material. The resonator’s characteristics are optimized, which makes it possible to obtain a field enhancement on the external surface of the resonator by more than two orders of magnitude. The influence of the NLE on the enhancement in the spectral wavelength range is investigated. It is shown that accounting for the NLE leads to a significant decrease in the near-field intensity.

When approaching the subwavelength or deep subwavelength scale, there is a fundamental trade-off between the ultimate shrinking size and the performance for miniaturized lasers. Herein, to overcome this trade-off, we investigated the excitonic gain nature of quasi-two-dimensional (quasi-2D) perovskites and revealed that both singlet excitons and polarons would make nearly the entire contribution within ∼50 ps to a high net gain of 558 cm-1. Inspired by the gain characteristic, we successfully shrank the quasi-2D perovskites laser to the subwavelength scale using only a layer of ultraviolet glue and a glass substrate in the vertical dimension. In spite of the compact and simple cavity structure, single-mode lasing with a highly linear polarization degree of 81% and a quality factor of 1635 was achieved. The extremely short cavity, excellent lasing performance, and simple structure of the quasi-2D perovskite laser are expected to provide insights into next-generation integrated laser sources.

Because of translational symmetry, electromagnetic fields confined within 2D periodic optical structures can be represented within the first Brillouin zone (BZ). In contrast, the wavevectors of scattered electromagnetic fields outside the lattice are constrained by the 3D light cone, the free-photon dispersion in the surrounding medium. Here, we report that light-cone surface lattice resonances (SLRs) from plasmonic nanoparticle lattices can be used to observe the radiated electromagnetic fields from extended BZ edges. Our coupled dipole radiation theory reveals how lattice geometry and induced surface plasmon dipole orientation affect angular distributions of the radiated fields. Using dye molecules as local dipole emitters to excite the light-cone SLR modes, we experimentally identified high-order BZ edges by directional, in-plane lasing emission. These results provide insight into nanolaser architectures that can emit at multiple wavelengths and in-plane directions simply by rotating the nanocavity lattice.

Semiconductor nanolaser has important research value and wide applications in many fields. However, it is still a challenge to obtain a nanolaser with tunability and high intensity at the nanoscale. Here, we report on lasers with two modes of emission wavelengths operating in near-infrared of nanohole filled with CoxGa0.6-xZnSe0.4 nanoparticle arrays at room temperature. The nanohole arrays are drawn on the photoresist by using the method of three-beam laser interferometric etching. Graphene with graphite which is coated on nanohole arrays is conducted by pulsed laser deposition (PLD) to construct the cavity. The CoxGa0.6-xZnSe0.4 nanoparticles are filled into the nanohole acting laser gain medium via the magnetic traction nanofilling technology. The results show that the laser at 868 and 903 nm is radiated, which can be tuned by changing the concentration and position of the filled nanoparticles in terms of wavelength and intensity. The nanolasers based on this approach represent an advantageous alternative to other design and fabrication methods. This nanoparticle nanolasers can be used in a micronano light source of an intelligent photonic chip.

A neuromorphic reservoir computing (RC) system using a semiconductor nanolaser (SNL) with double phase conjugate feedbacks (PCF) is proposed for the first time and demonstrated numerically. The prediction performance of such RC system is investigated via Santa Fe chaotic time series prediction task. The Purcell cavity-enhanced spontaneous emission factor F and the spontaneous emission coupling factor β are included in the rate equations, and the influences of F and β on the prediction performance of such RC system are analyzed extensively. For the purpose of comparison, the prediction performance of SNL-based RC system with single PCF is also considered. The simulation results indicate that, compared with the SNL-based RC system with single PCF, enhanced prediction performance can be obtained for the SNL-based RC system with double PCF. Moreover, the influences of bias current, the modulation depth of input signal, feedback strength, as well as feedback delay, are also taken into account. The proposed SNL-based RC system subject to double PCF in this paper has the potential to develop the RC-based neuromorphic photonic integrated circuit.

Near-infrared micro/nanolaser devices utilizing low-dimensional semiconductors can provide essential building blocks to achieve integrated optoelectronic devices and circuitry for advanced functionalities and are compatible with on-chip technologies. Although significant progress has been made through using narrow-band semiconductor micro/nanostructures to realize near-infrared stimulated radiation at room temperature, severe challenges still remain involving much lower quantum efficiencies and higher auger recombination. Herein, we report an experimental realization of a current-injection semiconductor polariton device made of a ZnO microwire via Ga-doping (ZnO:Ga MW) and p-type GaAs template. The device can emit polaritonic illumination directly from sharp edges of the hexagonal MW. The experimental results of angle-resolved electroluminescence measurements reveal a typical anticrossing feature between excitons and cavity modes, unambiguous evidence of the strong exciton-polariton coupling, with corresponding Rabi splitting energy extracted to be about 195 meV. As the applied bias goes above a certain value, electrically driven whispering gallery lasing action was achieved in the near-infrared spectrum, and the lasing features can be assigned to the exciton-polariton effect. The results not only can afford insights into the development of low-threshold coherent light sources via the exciton-polariton effect, but also can expand the fabrication of low-dimensional, near-infrared microlaser devices.

In this report, we propose an idea of connecting 1D photonic crystal (PhC) nanocavity with novel waveguide-like strain shapers in a polydimethylsiloxane substrate. In theory, the induced film-edge strain by the strain shapers can significantly enhance the wavelength tunability of PhC nanocavity under different applied stress. By our nanofabrication process, we realize this idea in the form of a tunable nanolaser. In experiments, the nanolaser shows the enhanced wavelength tunability both under stretching and compressive stress. By investigating the effects of PhC periods and length of the strain shapers, we obtain an optimized lasing wavelength tunability of −13.9 nm under every percentage strain variation in experiments. When further taking the 2nd -order mode in the nanocavity into consideration, we observe a wide lasing wavelength tuning range over 160 nm, which takes only the applied strain $\Delta \xi _{tot}$ of ±0.05. In addition to the large wavelength response beneficial for tunable nanolasers and optical strain sensors, we also believe that this waveguide-like strain shapers can serve as the optical interconnections at the same time in the flexible photonic circuits.

The past two decades have seen widespread efforts being directed toward the development of nanoscale lasers. A plethora of studies on single such emitters have helped demonstrate their advantageous characteristics such as ultrasmall footprints, low power consumption, and room-temperature operation. Leveraging knowledge about single nanolasers, the next phase of nanolaser technology will be geared toward scaling up design to form arrays for important applications. In this review, we discuss recent progress on the development of such array architectures of nanolasers. We focus on valuable attributes and phenomena realized due to unique array designs that may help enable real-world, practical applications. Arrays consisting of exactly two nanolasers are first introduced since they can serve as a building block toward comprehending the behavior of larger lattices. These larger-sized lattices can be distinguished depending on whether or not their constituent elements are coupled to one another in some form. While uncoupled arrays are suitable for applications such as imaging, biosensing, and even cryptography, coupling in arrays allows control over many aspects of the emission behavior such as beam directionality, mode switching, and orbital angular momentum. We conclude by discussing some important future directions involving nanolaser arrays.

A high-speed neuromorphic reservoir computing system based on a semiconductor nanolaser with optical feedback (SNL-based RC) under electrical modulation is proposed for the first time and demonstrated numerically. A Santa-Fe chaotic time series prediction task is employed to quantify the prediction performance of the SNL-based RC system. The effects of the Purcell cavity-enhanced spontaneous emission factor F and the spontaneous emission coupling factor β on the proposed RC system are analyzed extensively. It is found that, in general, increased F and β extend the range of good prediction performance of the SNL-based RC system. Moreover, the influences of bias current and feedback phase are also considered. Due to the ultra-short photon lifetime in SNL, the information processing rate of the SNL-based RC system reaches 10Gpbs. The proposed high-speed SNL-based RC system in this paper provides theoretical guidelines for the design of RC-based integrated neuromorphic photonic systems.

In this study, a quasi-classical model is proposed and developed for a surface plasmon (SP) nanolaser (spaser) system. The system is assumed to be composed of two-level quantum dots (QDs) coupled with a/an damping/amplifying cavity. Giving the both stable and unstable states, it is shown that the proposed model can describe the system nonlinear dynamics with an easier and more practical manner in comparison with the fully quantum-based models. Simulation results reveal that the instability in the system dynamical states can initiate in accordance with Ikeda map (as the universal map of instability in many optical systems) but does not progress accordingly. Instead, Duffing map and Henon map are recognized as the two characteristic maps of instability and chaos in the spaser system. More importantly, it is deduced that the SPs’ damping amplitude can be compensated if the feedback depth/nonlinear coefficient becomes as high/large as to induce chaotic regime in the transitional states between the two levels of QDs. A spaser with stimulated SPs can then be launched. Finally, an experimental evidence of a route to chaos is given in a nonlinear medium containing the flakes of reduced graphene oxide (RGO), dispersed inside a dielectric host to indicate the crucial role of feedback depth and nonlinearity. The proposed model can pave the way for designing the spaser systems in a practicable manner.

Plasmonics enables the manipulation of light beyond the optical diffraction limit1–4 and may therefore confer advantages in applications such as photonic devices5–7, optical cloaking8,9, biochemical sensing10,11 and super-resolution imaging12,13. However, the essential field-confinement capability of plasmonic devices is always accompanied by a parasitic Ohmic loss, which severely reduces their performance. Therefore, plasmonic materials (those with collective oscillations of electrons) with a lower loss than noble metals have long been sought14–16. Here we present stable sodium-based plasmonic devices with state-of-the-art performance at near-infrared wavelengths. We fabricated high-quality sodium films with electron relaxation times as long as 0.42 picoseconds using a thermo-assisted spin-coating process. A direct-waveguide experiment shows that the propagation length of surface plasmon polaritons supported at the sodium–quartz interface can reach 200 micrometres at near-infrared wavelengths. We further demonstrate a room-temperature sodium-based plasmonic nanolaser with a lasing threshold of 140 kilowatts per square centimetre, lower than values previously reported for plasmonic nanolasers at near-infrared wavelengths. These sodium-based plasmonic devices show stable performance under ambient conditions over a period of several months after packaging with epoxy. These results indicate that the performance of plasmonic devices can be greatly improved beyond that of devices using noble metals, with implications for applications in plasmonics, nanophotonics and metamaterials. A thermo-assisted spin-coating process followed by packaging is used to fabricate sodium films that are stable for several months, enabling the realization of plasmonic devices with state-of-the-art performance at near-infrared wavelengths.

Nanoscale laser sources with downscaled device footprint, high energy efficiency, and high operation speed are pivotal for a wide array of optoelectronic and nanophotonic applications ranging from on-chip interconnects, nanospectroscopy, and sensing to optical communication. The capability of on-demand lasing output with reversible and continuous wavelength tunability over a broad spectral range enables key functionalities in wavelength-division multiplexing and finely controlled light-matter interaction, which remains an important subject under intense research. In this study, we demonstrate an electrically controlled wavelength-tunable laser based on a CdS nanoribbon (NR) structure. Typical "S"-shaped characteristics of pump power dependence were observed for dominant lasing lines, with concomitant line width narrowing. By applying an increased bias voltage across the NR device, the lasing resonance exhibits a continuous tuning from 510 to 520 nm for a bias field in the range 0-15.4 kV/cm. Systematic bias-dependent absorption and time-resolved photoluminescence (PL) measurements were performed, revealing a red-shifted band edge of gain medium and prolonged PL lifetime with increased electric field over the device. Both current-induced thermal reduction of the band gap and the Franz-Keldysh effect were identified to account for the modification of the lasing profile, with the former factor playing the leading role. Furthermore, dynamical switching of NR lasing was successfully demonstrated, yielding a modulation ratio up to ∼21 dB. The electrically tuned wavelength-reversible CdS NR laser in this work, therefore, presents an important step toward color-selective coherent emitters for future chip-based nanophotonic and optoelectronic circuitry.

We report how the direction of quantum dot (QD) lasing can be engineered by exploiting high-symmetry points in plasmonic nanoparticle (NP) lattices. The nanolaser architecture consists of CdSe-CdS core-shell QD layers conformally coated on two-dimensional square arrays of Ag NPs. Using waveguide-surface lattice resonances (W-SLRs) near the Δ point in the Brillouin zone as optical feedback, we achieved lasing from the gain in CdS shells at off-normal emission angles. Changing the periodicity of the plasmonic lattices enables other high-symmetry points (Γ or M) of the lattice to overlap with the QD shell emission, which facilitates tuning of the lasing direction. We also increased the thickness of the QD layer to introduce higher-order W-SLR modes with additional avoided crossings in the band structure, which expands the selection of cavity modes for any desired lasing emission angle.

Nanowire laser arrays for integrated on-chip optical interconnects demand the uniformity of lasing wavelengths from different modules, which, however, is challenging owing to inevitable heterogeneity in subunit fabrication. Herein, we demonstrated a facile method to prepare uniform nanolaser arrays based on a transverse lateral Fabry–Perot (FP) microresonator built within single-crystalline organic microribbons of 1,4-bis((E)-2,4-dimethylstyryl)-2,5-dimethylbenzene (6M-DSB). Theoretically, spectroscopic and crystallographic results together reveal that short-axis brickwork-packing and long-axis uniaxial-alignment of 6M-DSB molecules result in a mixed Hj-type aggregation within microribbons. On the one hand, such a kind of Hj-type aggregation exhibits enhanced radiative decay and therefore 100% photoluminescence quantum yield for minimizing the singlet–triplet annihilation and reabsorption of laser photons owing to triplet absorption. On the other hand, the uniaxial alignment gives rise to a transverse lateral FP microresonator along the width of 6M-DSB microribbons, rather than a longitudinal microresonator in conventional nanowire lasers. By positioning a microribbon onto a PDMS pad with patterned grooves, only the suspended parts support transverse waveguiding and high quality FP resonances. A proof-of-concept 1 × 4 transverse nanolaser array constructed from the same microribbon was demonstrated with almost identical lasing thresholds, wavelengths and FP resonances, providing coupled lasing subunits for integrated organic photonics.

Based on the discrete source method, a rigorous approach has been developed and implemented that allows one to analyze light scattering by models of resonators of plasmonic nanolaser (SPASER). This approach takes into account all features of the boundary value problem for the Maxwell system, including the interaction of the resonators with the prism surface and the nonlocal screening effect, which is treated in the framework of the generalized nonlocal optical response (GNOR) model. It is shown that a resonator model with a dielectric core and a plasmonic shell has significant advantages over a layered model with a plasmonic core. The conditions are established under which the field can be enhanced by several orders of magnitude. It is shown that taking into account the GNOR leads to a decrease in the field intensity by 50%.

Ice accumulation on brass surfaces can lead to heat transfer inefficiency, equipment degradation, and potential accidents. To address this issue, superhydrophobic surface technology is utilized. This work aims to develop superhydrophobic nanostructured brass surfaces using the combination of nanolaser ablation and the deposition of silica nanoparticles to achieve the anti-icing property. Four distinct types of brass surfaces namely, the bare surface (BS), the lasered surface (LS), the coated surface (CS), and the coated-lasered surface (CLS) were prepared. The anti-icing performances of the fabricated samples including the effects of the surface structure, the droplet size, and the surface temperature were investigated and evaluated. The results showed that the delayed icing time increased with the increases in the apparent contact angle, the droplet size, and the surface temperature. When the apparent contact angle increased, the contact area between the droplet and the cooling substrate reduced, leading to the longer delayed icing time. With the deposition of silica nanoparticles and nanolaser treatment, CLS achieved the greatest apparent contact angle of 164.5°, resulting in the longest delayed icing time under all experimental conditions. The longest delayed icing time on CLS recorded in this study was 2584 s, which was 575%, 356%, and 27% greater than those on BS, LS, and CS, respectively. The study also revealed that the surface structure played a more crucial role in achieving the anti-icing property when compared to the surface temperature or the droplet size. The shortest delayed icing time on CLS at the lowest surface temperature and at the smallest droplet size was longer than those on BS and LS at all conditions. The results were also discussed in relation to a heat transfer model. The findings of this research can serve as an avenue for advancing knowledge on heat transfer enhancement and energy efficiency.

A high Q-factor of the nanocavity can effectively reduce the threshold of nanolasers. In this paper, a modified nanostructure composed of a silver grating on a low-index dielectric layer (LID) and a high-index dielectric layer (HID) was proposed to realize a nanolaser with a lower lasing threshold. The nanostructure supports a hybrid plasmonic waveguide mode with a very-narrow line-width that can be reduced to about 1.79 nm by adjusting the thickness of the LID/HID layer or the duty ratio of grating, and the Q-factor can reach up to about 348. We theoretically demonstrated the lasing behavior of the modified nanostructures using the model of the combination of the classical electrodynamics and the four-level two-electron model of the gain material. The results demonstrated that the nanolaser based on the hybrid plasmonic waveguide mode can really reduce the lasing threshold to 0.042 mJ/cm2, which is about three times lower than the nanolaser based on the surface plasmon. The lasing action can be modulated by the thickness of the LID layer, the thickness of the HID layer and the duty cycle of grating. Our findings could provide a useful guideline to design low-threshold and highly-efficient miniaturized lasers.

Band structures engineering of periodic optical structures enables the control of light propagation and localization. Although photons trapped inside 2D lattices can be described within the first Brillouin zone in reciprocal space, the wavevectors of scattered photons outside the lattice are limited by the 3D light cone, which depicts the free-photon dispersion in the surroundings. Because plasmonic nanoparticle lattices show unique dual properties of light trapping and strong scattering, this material platform is promising for investigations of radiative losses. This talk describes how light-cone surface lattice resonance (SLRs) from plasmonic nanoparticle lattices allow the observation of radiated electromagnetic fields. We theoretically predicted the angular distributions of the radiated fields, and experimentally probed the light-cone SLR modes by in-plane lasing emission. These results provide a nanolaser design strategy to achieve tunable lasing colors by lattice rotation.

In this report, we successfully demonstrated the room temperature operated SPP nanolaser on the graphene-insulator-metal (GIM) platform that can actively modulate the characteristics of SPP wave. The lasing threshold and emission peak of ZnO nanowire on aluminum with graphene were manipulated according to the amount of current injected to the graphene due to the nonreciprocal and thermal effect.

We report the first known example of a subwavelength plasmonic upconverting nanolaser with a low threshold. This perovskite-based plasmonic upconverting nanolaser features a record-small mode volume and an ultralow lasing threshold. Besides, we observed temporal coherence of the emission, which is an important feature of lasing. To co-optimize the pump photon absorption and the upconverted photon emission rate, the lasing result was made possible based on plasmonic titanium nitride. Moreover, we also demonstrated a new concept of lasing from a quantum emitter utilizing an intense localized electromagnetic field. A continuous-wave lasing was observed from single perovskite (CsPbBr3) quantum dot in a gap-plasmon nanocavity with an ultralow threshold of 1.9 Wcm-2 at 120 K. In the end, we will discuss the outlook for perovskite plasmonic nanolasers as on-chip light sources for bio-imaging, optical communication applications.

A plasmonic nanolaser architecture that can produce white-light emission is reported. A laser device is designed based on a mixed dye solution used as gain material sandwiched between two aluminum nanoparticle (NP) square lattices of different periodicities. The (±1, 0) and (±1, ±1) band-edge surface lattice resonance (SLR) modes of one NP lattice and the (±1, 0) band-edge mode of the other NP lattice function as nanocavity modes for red, blue, and green lasing respectively. From a single aluminum NP lattice, simultaneous red and blue lasing is realized from a binary dye solution, and the relative intensities of the two colors are controlled by the volume ratio of the dyes. Also, a laser device is constructed by sandwiching dye solutions between two Al NP lattices with different periodicities, which enables red-green and blue-green lasing. With a combination of three dyes as liquid gain, red, green, and blue lasing for a white-light emission profile is realized.

This work studies the gain from plasmonic quantum dot (QD) nanolaser. A metal/semiconductor/metal (MSM) structure was considered to attain plasmonic nanocavity with active region contains: QD, wetting layer (WL) and barrier layers. Band alignment between layers was used to predict their parameters. Momentum matrix element for transverse magnetic (TM) mode in QD structure was formulated. Waveguide Fermi energy was introduced and formulated, for the first time, in this work to cover the waveguide contribution (Ag metal layer) in addition to the active region. High net modal gain was obtained when the waveguide Fermi energy was taken into account which means that the increment comes from the material gain not from the confinement factor. The change in waveguide Fermi energy in the valence band explained the high gain, where the valence band QD states are fully occupied referring to an efficient hole contribution.

The discrete source method is generalized so as to investigate the nonlocal effects in multilayered particles on a substrate. The scheme for constructing an approximate solution and the corresponding numerical algorithm are described in detail. The developed approach is used to study the optical characteristics of 3D cavities of plasmonic nanolasers. It is shown that the amplitude of surface plasmon resonance and the amplification factor of the near-field intensity are reduced significantly when the nonlocal effects are taken into account. It is also shown that the amplification factor can be increased by more than twice by varying the material and thickness of the cavity shell and the direction of the incident wave.

We report on the fabrication of ordered arrays of InGaN/GaN nanowire quantum disks by a top-down selective-area sublimation method. Using a combination of two-dimensional molecular beam epitaxy of ...

Formamidinium (FA) perovskites have exhibited outstanding optoelectronic properties in solar cells and light-emitting diodes. However, their development on nanolaser application have rarely been ex...

Aim: To compare the safety and efficacy of a new nanolaser photofragmentation technique of cataract surgery with ultrasound phacoemulsification. Method: A cohort of 20 patients underwent ultrasound phacoemulsification in one eye (group I) and nanosecond laser fragmentation in the other eye (group II). All cataracts were classified as stage 3 of cataract progression, i.e. nuclear opalescence (NO) was NO2-NO3 according to the used Lens Opacities Classification System III. We observed uncorrected visual acuity (UCVA expressed in decimal units) before and after surgery, as well as corneal endothelial cell density (ECD), the percentage of hexagonal cells and the pleomorphism index (PI) and corneal thickness (CT) before surgery and 7 days after surgery. Results: In all 40 eyes the course of surgery was uncomplicated. BCVA was 0.70 ± 0.10 in group I before surgery, in group II 0.68 ± 0.10, and 7 days after surgery in group I 0.98 ± 0.05 and in group II 0.98 ± 0.04 (p-NS). Average ECD (cells/mm2) before surgery in group I was 2508 ± 205.54 bb/mm2 and in group II 2472.5 ± 287.78 bb/mm2. After surgery in group I this was 2024.92 ± 271.50 bb/mm2 and in group II 2138.50 ± 390.85 bb/mm2. The differences in the loss of endothelial cells between both groups were statistically insignificant. In a comparison of the difference of both groups upon average incidence of hexagonal cells before and after surgery, the differences were statistically insignificant, as they were upon a comparison of the differences of corneal thickness. In all the observed parameters we therefore did not record any statistically significant differences. Conclusion: Nanolaser lens photofragmentation and ultrasound phacoemulsification can be considered of equal value from the perspective of a comparison of both methods on perioperative influence on the corneal epithelium.

The capability of nanolasers to generate coherent light in small volume resonators has made them attractive to be implemented in future ultra-compact photonic integrated circuits. However, compared to conventional lasers, nanolasers are also known for their broader spectral linewidths, that are usually on the order of 1 nm. While it is well known that the broad linewidths in light emitters originate from various noise sources, there has been no rigorous study on evaluating the origins of the linewidth broadening for nanolasers to date to the best of our knowledge. In this manuscript, we investigate the impact of fundamental thermal fluctuations on the nanolaser linewidth. We show that such thermal fluctuations are one of the intrinsic noise sources in a sub-wavelength metal-clad nanolaser inducing significant linewidth broadening. We further show that with the reduction of the nanolaser’s dimensions, i.e., mode volume, and the increase of the ambient temperature, such linewidth broadening is enhanced, due to the effect of more pronounced fundamental thermal fluctuation. Specifically, we show that the finite linewidths induced by the thermal fluctuations at room temperature are 1.14nm and 0.16nm, for nanolasers with core radii of 250nm and 750nm, respectively. Although our study was performed on a metallo-dielectric nanolaser, it is reasonable to assume that, in general, other nanolaser architectures are also more prone to thermal fluctuations, and hence exhibit larger finite linewidths than conventional large mode volume lasers.

Recently, many researches are reported on using germanium in silicon-based lasers but acquiring this potential for a plasmonic nanolaser may also be important for development of silicon-compatible plasmon sources. In this paper, a custom-shaped nanocavity plasmon source based on highly doped tensile-strained germanium/silicon-germanium multiple quantum well gain medium is introduced and theoretically investigated. We have used a semi-classical macroscopic rate equation model for calculation of the output performance characteristics. Also, modal analysis has been done based on FDTD method. The proposed nanolaser has a tiny footprint of 0.1225 μm2, possible room temperature performance, and fabrication process based on a silicon substrate. The output performance of the nanolaser structure as estimated is noticeable and the calculated results, using some previously reported experimental data and redundant software double checking, show acceptable compatibility. In 1550-nm output wavelength, it provides 15.6 mW output power in the 21-mA threshold current and 600 μW in 1-mA pump current, while maintaining its performance in a wide spectral bandwidth about 2 THz. It also can be electrically modulated by the pump current up to 3 GHz. This remarkable performance is achieved, thanks to the high Purcell factor of the parabolically notched nanocavity of about 700 and its high quality factor of about 58.

As an ideal miniaturized light source, wavelength-tunable nanolasers capable of emitting a wide spectrum stimulate intense interests for on-chip optoelectronics, optical communications, and spectroscopy. However, realization of such devices remains a major challenge because of extreme difficulties in achieving continuously reversibly tunable gain media and high quality (Q)-factor resonators on the nanoscale simultaneously. Here, exploiting single bandgap-graded CdSSe NWs and a Fabry-Pérot/whispering gallery mode (FP/WGM) coupling cavity, a free-standing fiber-integrated reversibly wavelength-tunable nanolaser covering a 42 nm wide spectrum at room temperature with high stability and reproducibility is demonstrated. In addition, a 1.13 nm tuning spectral resolution is realized. The substrate-free device design enables integration in optical fiber communications and information. With reversible and wide, continuous tunability of emission color and precise control per step, our work demonstrates a general approach to nanocavity coupling affording high Q-factors, enabling an ideal miniaturized module for a broad range of applications in optics and optoelectronics, with optical fiber integration.

This study models quantum dot (QD) plasmonic nanolaser. A metal/semiconductor/metal (MSM) structure was considered to attain plasmonic nanocavity. The active region (semiconductor layers) contains the following: QD, wetting layer (WL), and barrier layers. Band alignment between layers was used to predict their parameters. Momentum matrix element for transverse magnetic (TM) mode in QD structure was formulated. Waveguide Fermi energy was introduced and formulated, for the first time, in this work to cover the waveguide contribution (Ag metal layer) in addition to the active region. The high net modal gain was obtained when the waveguide Fermi energy was considered which meant that the increment comes from the material gain, not from the confinement factor. The obtained results were reasoned the high gain due to the change in waveguide Fermi energy in the valence band, where the valence band QD states are fully occupied that are referring to an efficient hole contribution.

Organometal halide perovskites have recently emerged with a huge potential for photovoltaic applications. Moreover, preparation of high-quality perovskite crystals with controlled morphology is of great significance for the fundamental studies such as optical and electrical properties, as well as the applications. Here, we report a one-pot solvothermal process to synthesize sheet-shaped CH3NH3PbBr3 single crystals with the lateral size of 100 µm and the thickness of 3–8 µm. Furthermore, a controlled etching behavior on the crystalline surface was demonstrated, which could be the irregular collapse of the crystalline surface caused by the local accumulation of methylammonium cations. Using this technique, CH3NH3PbBr3 single crystal sheets could be used in the various optoelectronic devices, such as nanolaser, optical sensors, photodetectors and field effect transistors.

The problem of the influence of the nonlocality effect on the optical characteristics of plasmon nanolaser resonators is considered. This was performed within the framework of the generalized nonlocal optical response model; we took the nonlocality into account. Based on an extension of the discrete sources method, we performed a comparative analysis of the frequency characteristics of the field intensity in both the far and near zones, depending on the geometry of the resonator. The shapes of layered nonspherical resonators were considered. We established that, taking the nonlocality effect into account, one obtains a decrease of the intensity of plasmon resonance by up to 2.5 times.

Light-matter interactions with two-dimensional materials gained significant attention in recent years, leading to the reporting of weak and strong coupling regimes and effective nanolaser operation with various structures. Particularly, future applications involving monolayer materials in waveguide-coupled on-chip-integrated circuitry and valleytronic nanophotonics require controlling, directing, and optimizing photoluminescence. In this context, photoluminescence enhancement from monolayer transition-metal dichalcogenides on patterned semiconducting substrates becomes attractive. It is demonstrated in our work using focused-ion-beam-etched GaP and monolayer WS2 suspended on hexagonal boron nitride buffer sheets. We present an optical microcavity approach capable of efficient in-plane and out-of-plane confinement of light, which results in a WS2 photoluminescence enhancement by a factor of 10 compared to that of the unstructured substrate at room temperature. The key concept is the combination of interference effects in both the horizontal direction using a bull's-eye-shaped circular Bragg grating and in the vertical direction by means of a multiple-reflection model with optimized etch depth of circular air-GaP structures for maximum constructive interference effects of the applied pump and expected emission light.

The time delay signature (TDS) concealment properties of a novel semiconductor nanolaser subject to double chaotic optical injections are investigated numerically. The TDS concealment is evaluated by the peak size of the autocorrelation function (ACF). The effects of feedback rate, injection rate, frequency detuning, Purcell cavity-enhanced spontaneous emission factor, and spontaneous emission coupling factor on the TDS concealment are carefully examined. It is found that, with the double chaotic optical injections, the TDS can be concealed in wide ranges of feedback rate, injection rate, and frequency detuning. Moreover, better TDS concealment can be achieved for a smaller frequency detuning and a larger injection rate. The 2-D maps of peak size of ACF further show that the range of parameter space contributing to better TDS concealment is wider for a moderate Purcell cavity-enhanced spontaneous emission factor and a smaller spontaneous emission coupling factor. These results may be interesting for the enhanced chaotic sources on-a-chip based on novel semiconductor nanolasers.

In this article two optically pumped nanorod-based plasmonic nanolasers which composed of two coupled metal-insulator-semiconductor (MIS) hybrid plasmonic waveguides are investigated. In the first structure, a common metallic nanorod is utilized to construct a semiconductor-insulator-metal-insulator-semiconductor (SIMIS) nanostructure while in the second one, the semiconductor part is shared and a metal-insulator-semiconductor-insulator-metal (MISIM) based plasmonic nanolaser is formed. Simulation results based on the finite element method (FEM) show that the SIMIS structure with nanorods’ radii of 40 nm and insulator layer thickness of more than 12.67 nm has lower threshold and simultaneously lower normalized mode area at the lasing wavelength of 490 nm compared to the previously reported MIS nanostructure with the same parameters. The simulation results for the second proposed structure show that the MISIM based spaser has a lower effective mode index and consequently lower wave number at the wavelength of 490 nm, compared to both SIMIS and MIS based nanocavities. This results in less challenge for coupling to on-chip waveguides. The cavity length of the presented nanorod-based spasers has been optimized by considering the lasing mode propagation distance as the nanocavity length which leads to a better light matter interaction enhancement.

Plasmonic lasers amplify the light coupled to oscillating electrons so that by adding momentum it becomes viable to have dimensions beyond diffraction limit of course this ability to focus light has the drawback of high losses at the metal surface. In this research considering the properties of periodic structures we formed the idea that placing plasmonic lasers in periodic structures may lead to distinct properties which are not seen in single plasmonic lasers. Simulation results for ZnO nanowire plasmonic laser show that in one dimensional periodic structures the dependency of the radiation light to the angle of incidence is increased so that one additional degree of freedom is obtained for controlling the nanolaser operation besides the minimum diameter of the nanowire to observe lasing is decreased from 120nm to 80 nm.

Surface plasmon polariton (SPP) nanolaser, which can achieve all-optical circuits, is a major research topic in the field of micro light source. In this work, we proposed a novel double-mode SPP nanolaser which is consisted of InGaAsP high-index dielectric, Ag metal, and T-shape MgF2 low-index dielectric. The best performances of the proposed waveguide can be obtained in the conditions of λ = 675 nm, R = 70 nm, Gap = 3 nm, and w = 2 nm, which is corresponded the incident wavelength, radius of nanowires, gap, and width, respectively. In that conditions, the mode area and threshold can be reached at 0.05 λ2 and 1.23 × 104 cm−1. Furthermore, the propagation distance and the confinement factor can reach 1200 nm and 0.33, respectively. It shows that the proposed device has significant potential in ultrahigh density plasmonic and photonic integrated circuit.

Nanolasers are expected to be integrated on chips as miniaturized coherent light sources, and their application is strongly dependent on their lasing behavior. In this work, the lasing behavior of a single hexagonal ZnO pyramid (HZOP) is tailored by tuning the electronic bandgap with pressure. The lasing of the HZOP nanolaser is dominated by a helical whispering-gallery-like mode, and the lasing threshold varies little with increasing pressure. All lasing peaks of HZOP are limited in a spectral prescreen window on the right shoulder of the fluorescence emission and gradually blue-shift accompanied by several abrupt hops with increasing pressure. This feature of a spectral prescreen window originates from the strong coupling between excitons, and the coupling is described by a dispersive complex refractive index. These results provide a new perspective to tune and switch the lasing mode of a nanolaser with precision by the pressure-induced bandgap broadening of a semiconductor.

International audience; A Markov model of semiconductor nanolaser is constructed in order to describe finely the effects of quantum fluctuations in the dynamics of the laser, in particular by considering the transition to lasing. Nanolasers are expected to contain only a small number of emitters, whose semiconductor bands are simulated using true carrier energy states. The model takes into account carrier-carrier interactions in the conduction and valence bands, but the result is a huge Markov chain that is often too demanding for direct Monte-Carlo simulation. We introduce here a technique to split the whole chain into two subchains, one referring to thermalization events within the bands and the other to laser photonic events of interest. The model is applied to the analysis of laser transition and enlightens the coexistence of a pulse regime triggered by the quantum nature of the photon with the birth of the known coherent cw regime. This conclusion is highlighted by calculated time traces. We show that on the ultrasmall scale of nanolasers, we are unable to define perfectly the threshold.

With the recent growth of Artificial Intelligence and Neural Networks systems, alternatives to the Von Neumann architecture are on development to run these algorithms efficiently in terms of speed, size and power consumption [1] – [3] . Electrical transmission of information is highly dissipative, transistors are reaching their size limit since their functionalities are affected by quantum effects and digital computing is falling short to manage the vast number of continuous variables involved in AI algorithms at a fast pace.

Spontaneous symmetry breaking (SSB) is a fundamentally important process that underlies many outstanding physical phenomena, such as phase transitions in metamaterials, and that can be exploited for a wide variety of applications. In particular, SSB has been observed in single coherently driven micro or macro ring resonators, where it respectively occurs between the forward and the counter propagative waves [1] , and between the two elliptically polarized components of the resonator [2] , and it has notably been proposed for new computing schemes. Nanodevices constitute a highly promising platform that could be harnessed for targeting a reduction of the photon number or improved integration capacity. SSB has recently been observed in evanescently coupled nanolasers, incoherently driven above the laser threshold, as the breaking of the mirror (or left/right) symmetry [3] . However, incoherent pumping suffers from thermal noise and a lack of control since the only control parameter is the pumping level in the nanolaser system, whereas the detuning can also be changed in the coherently driven system. In addition, most theoretical developments on few photon SSB in nonlinear coupled cavities have been carried out in a coherently driven-dissipative framework and have notably predicted important quantum features such as entanglement [4] . These driven-dissipative nonlinear coupled-cavity models constitute a paradigm of open quantum systems. Importantly, SSB in a coherently driven-dissipative system has not been demonstrated to date.

High-Q factor can enhance the interaction between light and matter, which is an important parameter to decrease the threshold of nanolasers. Here, we theoretically propose an eccentric nanoring structure with a high and controllable Q factor to realize a low-threshold and controllable nanolaser by amplifying the quasi-bound states in the continuum (quasi-BIC). The designed nanostructure supports a quasi-BIC because of the symmetry protection-breaking of the nanostructure. The quasi-BIC has a very high Q factor of about 9.6×104 and can also be adjusted by changing structural parameters. We use the energy level diagram of the four-level two-electron system to study the lasing action of the eccentric nanoring structure. The results show that the nanolaser has a relatively low threshold of about 6.46 μJ/cm2. Furthermore, the lasing behavior can be tuned by controlling the structural parameters of the eccentric circular ring structure.

Plasmonic nanolasers based on the spatial localization of surface plasmons (SPs) have attracted considerable interest in nanophotonics, particularly in the desired application of optoelectronic and photonic integration, even breaking the diffraction limit. Effectively confining the mode field is still a basic, critical and challenging approach to improve optical gain and reduce loss for achieving high performance of a nanolaser. Here, we designed and fabricated a semiconductor/metal (ZnO/Al) core–shell nanocavity without an insulator spacer by simple magnetron sputtering. Both theoretical and experimental investigations presented plasmonic lasing behavior and SP-exciton coupling dynamics. The simulation demonstrated the three-dimensional optical confinement of the light field in the core–shell nanocavity, while the experiments revealed a lower threshold of the optimized ZnO/Al core–shell nanolaser than the same-sized ZnO photonic nanolaser. More importantly, the blue shift of the lasing mode demonstrated the SP-exciton coupling in the ZnO/Al core–shell nanolaser, which was also confirmed by low-temperature photoluminescence (PL) spectra. The analysis of the Purcell factor and PL decay time revealed that SP-exciton coupling accelerated the exciton recombination rate and enhanced the conversion of spontaneous radiation into stimulated radiation. The results indicate an approach to design a real nanolaser for promising applications.

We report on Purcell enhancement of single quantum dot and a low-threshold topological nanolaser in 2D topological photonic crystal nanocavity based on the second-order corner state. In the fabricated cavities with a low density of quantum dots, we demonstrate the Purcell enhancement of single quantum dot. In the cavities with a high density, a topological laser is observed with a low threshold of about $1\mu\mathrm{W}$ .

International audience; We theoretically analyze the robustness to potential distortion of mode-locking in a harmonic cavity nanolaser sustaining oscillation of Hermite-Gaussian modes. Different types of imperfections of the harmonic potential that create the Hermite-Gaussian modes are considered: the non-parabolicity of the potential and the possible random errors in the shape of the potential. The influence of the different laser parameters, including the Henry factors of the gain medium and the saturable absorber, on the robustness of the mode-locked regime is discussed in detail.