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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.

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.

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.

Plasmonics offers a unique opportunity to break the diffraction limit of light and bring photonic devices to the nanoscale. As the most prominent example, an integrated nanolaser is a key to truly nanoscale photonic circuits required for optical communication, sensing applications and high-density data storage. Here, we develop a concept of an electrically driven subwavelength surface-plasmon-polariton nanolaser, which is based on a novel amplification scheme, with all linear dimensions smaller than the operational free-space wavelength λ and a mode volume of under λ 3/30. The proposed pumping approach is based on a double-heterostructure tunneling Schottky barrier diode and gives the possibility to reduce the physical size of the device and ensure in-plane emission so that the nanolaser output can be naturally coupled to a plasmonic or nanophotonic waveguide circuitry. With the high energy efficiency (8% at 300 K and 37% at 150 K), the output power of up to 100 μW and the ability to operate at room temperature, the proposed surface plasmon polariton nanolaser opens up new avenues in diverse application areas, ranging from ultrawideband optical communication on a chip to low-power nonlinear photonics, coherent nanospectroscopy, and single-molecule biosensing.

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.

Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions. We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures, revealing high Q-factors of 1250 ± 90 corresponding to end-facet reflectivities of R = 0.73 ± 0.02. By using optimised direct–indirect band alignment in the active region, we demonstrate a well-refilling mechanism providing a quasi-four-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds (~6 μJ cm−2 pulse−1) for III–V nanowire lasers. Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements., Lasers: Record-breaking lasing nanowires Persistent short pulses of near-infrared laser light can be produced at record low thresholds using tiny nanowire lasers, suitable for small-scale optoelectronic devices, including optical computing chips. The technology has been developed and demonstrated by researchers in the UK, led by Patrick Parkinson at the University of Manchester. Their system is based on semiconducting nanowires composed of gallium arsenide phosphide and gallium arsenide. It combines both key functions of a laser in one material, as the gain medium that amplifies the light emission and the cavity medium for containing and manipulating the light. The researchers engineered the precise behavior of the nanowires to demonstrate highly optimized nano-lasing performance at room temperature lasing thresholds. Their work addresses and overcomes significant challenges that have been limiting developments in this promising field.

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.

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...

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.

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.

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 $1\mu\mathrm{W}$ .

Using the hybrid plasmonic waveguide (HPW) principle as a basis, a new planar symmetric Ag-dielectric-SiO2 hybrid waveguide structure is designed and applied to nanolasers. First, the effects on the electric field distribution and the characteristic parameters of the waveguide structure of changes in the material, the nanometer radius, and the dielectric layer thickness were studied in detail using the finite element method with COMSOL Multiphysics software. The effects of two different dielectric materials on the HPW were studied. It was found that the waveguide performance could be improved effectively and the mode propagation loss was reduced when graphene was used as the dielectric, with the minimum effective propagation loss reaching 0.025. Second, the gain threshold and the quality factor of a nanolaser based on the proposed hybrid waveguide structure were analyzed. The results showed that the nanolaser has a lasing threshold of 1.76 μm−1 and a quality factor of 109 when using the graphene dielectric. A low-loss, low-threshold laser was realized, and the mode field was constrained by deep sub-wavelength light confinement. This structure has broad future application prospects in the integrated optics field and provides ideas for the development of subminiature photonic devices and high-density integrated circuits.

In this paper, a possible way to achieve lasing from THz to extreme UV domain due to stimulated scattering of graphene plasmons on the free electrons is considered. The analytical-quantitative description of the proposed FEL scheme is based on the self-consistent set of the Maxwell--Vlasov equations. We study the downconversion as well as the upconversion. It is shown that the coherent downconversion of infrared radiation to THz one can be achieved using a source of very non-relativistic electrons at the resonant coupling with the graphene plasmons. Due to the strongly confined graphene plasmons, the upconversion of mid-infrared to extreme UV radiation can be achieved with the mildly relativistic electron beams. The latter is a promising mechanism for the tabletop short-wavelength free electron nanolaser., 16 pages, 3 figures

A single-nanoparticle plasmon laser with ultratight optical confinement in all three dimensions is a long-cherished but yet to be realized goal. Here we propose an experimentally realizable plasmon laser using a single nanorod. We show that, by harnessing a Au-nanorod cavity with a large gain from a Purcell-enhanced stimulated emission rate and greatly suppressed high-order mode dissipation, it is possible to implement a dipole-mode plasmon laser with accessible material parameters. Our approach may lead to a real single-nanoparticle plasmon laser with three-dimensional ultraconfinement and offers an opportunity to explore and utilize the enhanced light-matter interaction at a lower dimension.

AIP Advances, 10 (10), ISSN:2158-3226

ZnO nanowire-based surface plasmon polariton (SPP) nanolasers with metal&ndash, insulator&ndash, semiconductor hierarchical nanostructures have emerged as potential candidates for integrated photonic applications. In the present study, we demonstrated an SPP nanolaser consisting of ZnO nanowires coupled with a single-crystalline aluminum (Al) film and a WO3 dielectric interlayer. High-quality ZnO nanowires were prepared using a vapor phase transport and condensation deposition process via catalyzed growth. Subsequently, prepared ZnO nanowires were transferred onto a single-crystalline Al film grown by molecular beam epitaxy (MBE). Meanwhile, a WO3 dielectric interlayer was deposited between the ZnO nanowires and Al film, via e-beam technique, to prevent the optical loss from dominating the metallic region. The metal&ndash, oxide&ndash, semiconductor (MOS) structured SPP laser, with an optimal WO3 insulating layer thickness of 3.6 nm, demonstrated an ultra-low threshold laser operation (lasing threshold of 0.79 MW cm&minus, 2). This threshold value was nearly eight times lower than that previously reported in similar ZnO/Al2O3/Al plasmonic lasers, which were &asymp, 2.4 and &asymp, 3 times suppressed compared to the SPP laser, with WO3 insulating layer thicknesses of 5 nm and 8 nm, respectively. Such suppression of the lasing threshold is attributed to the WO3 insulating layer, which mediated the strong confinement of the optical field in the subwavelength regime.

We report continuous-wave (CW) lasing at 535 nm from a single lead halide perovskite (CsPbBr3) quantum dot (PQD) in a gap plasmon nanocavity with an ultralow threshold (lower than 90 mWcm-2) under 4 K. The ultrasmall mode volume dramatically enhances the light-matter interaction to achieve CW lasing. By raising the temperature, a clear lasing threshold can be observed at temperatures above 80 K. The demonstration of single QD lasing, which operates in the strong coupling regime, provides a new approach for realizing electrically driven lasing and integration into ultracompact optoelectronic devices. The detail mechanism of plasmonic lasing will be discussed.

Plasmonic nanolasers have excellent potential for ultrafast modulation due to their ability to accelerate spontaneous emission and increase the modulation bandwidth. Critical metrics of the nanolaser dynamics include photon lifetime, spontaneous emission rate, and polarization lifetime. However, these processes have significantly different lifetimes, which presents a challenge for modeling. Classical rate equations fail to predict the modulation behavior accurately. In this talk, we cover some history of the numerical modeling of nanoscale lasers and discuss our efforts on developing accurate computational approaches to describing modulated plasmonic nanolasers. We also highlight the regimes where multi-scale methods can still be used efficiently.

Lead halide perovskite materials have recently received considerable attention for achieving an economic and tunable laser owing to their solution-processable feature and promising optical properties. However, most reported perovskite-based lasers operate with a large lasing-mode volume, resulting in a high lasing threshold due to the inefficient coupling between the optical gain medium and cavity. Here, we demonstrate a continuous-wave nanolasing from a single lead halide perovskite (CsPbBr3) quantum dot (PQD) in a plasmonic gap-mode nanocavity with an ultralow threshold of 1.9 Wcm-2 under 120 K. The calculated ultrasmall mode volume (∼0.002 λ3) with a z-polarized dipole and the significantly large Purcell enhancement at the corner of the nanocavity inside the gap dramatically enhance the light-matter interaction in the nanocavity, thus facilitating lasing. The demonstration of PQD nanolasing with an ultralow-threshold provides an approach for realizing on-chip electrically driven lasing and integration into on-chip plasmonic circuitry for ultrafast optical communication and quantum information processing.

A highly efficient nanocavity formed by optically coupled nanostructures is achieved by optimization of the collective Mie resonances in a one-dimensional array of semiconductor nanoparticles. Analysis of quasi-normal multipole modes enables us to reveal the close relation between the collective Mie resonances and Van Hove singularities. On the basis of these concepts, we experimentally demonstrate a directional GaAs nanolaser at cryogenic temperatures with well-defined, in-plane emission, which, moreover, can be controlled by selective excitation. The lasing threshold is shown to be significantly reduced by optimizing the interparticle gap such that the optimal near-field confinement is achieved at a resonant wavelength corresponding to the highest gain of GaAs. We show that the lasing performance of this nanolaser is orders of magnitude better than a nanowire-based laser of the same dimensions. The present work provides design guidelines for high performance in-plane emission nanolasers, which may find applications in future photonic integrated circuits.

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.

The topological lasers, which are immune to imperfections and disorders, have been recently demonstrated based on many kinds of robust edge states, being mostly at microscale. The realization of 2D on-chip topological nanolasers, having the small footprint, low threshold and high energy efficiency, is still to be explored. Here, we report on the first experimental demonstration of the topological nanolaser with high performance in 2D photonic crystal slab. Based on the generalized 2D Su-Schrieffer-Heeger model, a topological nanocavity is formed with the help of the Wannier-type 0D corner state. Laser behaviors with low threshold about 1 $\mu W$ and high spontaneous emission coupling factor of 0.25 are observed with quantum dots as the active material. Such performance is much better than that of topological edge lasers and comparable to conventional photonic crystal nanolasers. Our experimental demonstration of the low-threshold topological nanolaser will be of great significance to the development of topological nanophotonic circuitry for manipulation of photons in classical and quantum regimes., Comment: 15 pages, 4 figures

Arrays of metallic particles patterned on a substrate have emerged as a promising design for on-chip plasmonic lasers. In past examples of such devices, the periodic particles provided feedback at a single resonance wavelength, and organic dye molecules were used as the gain material. Here, we introduce a flexible template-based fabrication method that allows a broader design space for Ag particle-array lasers. Instead of dye molecules, we integrate colloidal quantum dots (QDs), which offer better photostability and wavelength tunability. Our fabrication approach also allows us to easily adjust the refractive index of the substrate and the QD-film thickness. Exploiting these capabilities, we demonstrate not only single-wavelength lasing but dual-wavelength lasing via two distinct strategies. First, by using particle arrays with rectangular lattice symmetries, we obtain feedback from two orthogonal directions. The two output wavelengths from this laser can be selected individually using a linear polarizer. Second, by adjusting the QD-film thickness, we use higher-order transverse waveguide modes in the QD film to obtain dual-wavelength lasing at normal and off-normal angles from a symmetric square array. We thus show that our approach offers various design possibilities to tune the laser output., ACS Nano, 14 (5), ISSN:1936-0851, ISSN:1936-086X

We demonstrate a circularly polarized laser with the metal-gallium-nitride gammadion nanocavities. The ultraviolet lasing signal was observed with the high circular dichroism at room temperature under pulsed optical pump conditions. Without external magnetism which breaks the time-reversal symmetry to favor optical transitions of a chosen handedness, the coherent outputs of these chiral nanolasers show a dissymmetry factor as high as 1.1. The small footprint of these lasers are advantageous for applications related to circularly polarized photons in future integrated systems, in contrast to the bulky setup of linearly-polarized lasers and quarter-wave plates.

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.

Results from the electromagnetic modeling of the threshold conditions of hybrid plasmon modes of a laser based on a silver nanotube with an active core and covered with an active shell are presented. We study the modes of such a nanolaser that have their emission wavelengths in the visible-light range. Our analysis uses the mathematically grounded approach called the lasing eigenvalue problem (LEP) for the set of the Maxwell equations and the boundary and radiation conditions. As we study the modes exactly at the threshold, there is no need to invoke nonlinear and quantum models of lasing. Instead, we consider a laser as an open plasmonic resonator equipped with an active region. This allows us to assume that at threshold the natural-mode frequency is real-valued, according to the situation where the losses, in the metal and for the radiation, are exactly balanced with the gain in the active region. Then the emission wavelength and the associated threshold gain can be viewed as parts of two-component eigenvalues, each corresponding to a certain mode. In the configuration considered, potentially there are three types of modes that can lase: the hybrid localized surface plasmon (HLSP) modes of the metal tube, the core modes, and the shell modes. The latter two types can be kept off the visible range in thin enough configurations. Keeping this in mind, we focus on the HLSP modes and study how their threshold gain values change with variations in the geometrical parameters of the nanotube, the core, and the shell. It is found that essentially a single-mode laser can be designed on the difference-type HLSP mode of the azimuth order m = 1, shining in the orange or red spectral region. Furthermore, the threshold values of gain for similar HLSP modes of order m = 2 and 3 can be several times lower, with emission in the violet or blue parts of the spectrum.

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.

The talk highlights our recent efforts in modelling the nonlinear optical processes integrated with nanophotonic devices with a particular emphasis on lasing with feedback from topologically exotic metasurfaces. We have developed a computational multiphysics framework that provides a comprehensive understanding of the nonlinear light-matter interaction dynamics in nanophotonic devices. Our technique relies on a semi-classical approach that utilises carrier kinetics to model the nonlinear media in the time domain, where the rate equations are coupled to the Maxwell equations to provide a full-wave multiphysics framework for modelling nonlinear nanophotonic structures. The framework has been applied to a large number of nonlinear processes, including the enhancement of optical limiting in a plasmonic metasurface, spacing from a nanohole array, two-photon absorption, random lasing, and many others. The talk presents a computational effort in modeling nanophotonics devices coupled to two-photon absorbing media. A six-level system is used to model the kinetics of two-photon absorption with organic dyes. This model is successfully used to match the spectral response of the organic 4,4’-bis(diphenylamino) stilbene (BDPAS) at low and high excitation energies and can be employed for accurate full-wave analysis of structured nanophotonic devices with multi-photon absorption media. Then, the numerical analysis of a dielectric metasurface-based nanolaser and the experimental validation of the numerical results is chosen as the central theme, considering nanolasers with feedback from exotic all-dielectric metasurfaces with bound states in the continuum (BICs). Metasurfaces find a wide variety of applications due to their versatile functionalities and more straightforward fabrication vs bulk metamaterials. However, their spectral response is generally broad, hindering their applicability to devices requiring sharp spectral features. We utilise the exotic phenomenon of BICs to realise high Q-factor resonances in all-dielectric metasurfaces. The designed BIC-based metasurfaces exhibit operation independent of polarisation with resonances in the visible.

In the present talk we discuss the application of Template-Assisted Selective Epitaxy (TASE) for the monolithic integration of III-V active photonic devices on silicon. The main concept of TASE relies on the guided growth of III-Vs within a confined oxide template. At one extremity of the template there is access to silicon to start the nucleation, and subsequently it is the template which guides the growth progression. This decoupling of the resulting geometry from the growth mode and substrate orientation, results in a larger processing window as we no longer rely on the growth conditions to tune the geometry, as well as a number of other advantages. A further unique advantage of TASE for silicon photonics applications is that it allows for the truly local integration of III-V material at precisely defined positions, since the location of the III-V may be defined with nm-scale precision in the same lithographic step as silicon passives. TASE was originally developed for electronics, but in recent years we have expanded it to enable several photonic devices. In the present talk, I will discuss our work on GaAs and InP microdisk lasers fabricated by either direct growth or via the use of micro-substrates. These devices show lasing at room temperature around 870 nm with thresholds of about 10 pJ/pulse. We also explore the use of metal-clad cavities for further light confinement.

Plasmonic-waveguide lasers, which exhibit subdiffraction limit lasing and light propagation, are promising for the next-generation of nanophotonic devices in computation, communication, and biosensing. Plasmonic lasers supporting waveguide modes are often based on nanowires grown with bottom-up techniques that need to be transferred and aligned for use in optical circuits. Here, we demonstrate a monolithically fabricated ZnO/Al plasmonic-waveguide nanolaser compatible with the fabrication requirements of on-chip circuits. The nanolaser is designed with a plasmonic metal layer on the top of the laser cavity only, providing highly efficient energy transfer between photons, excitons, and plasmons, and achieving lasing in the ultraviolet region up to 330 K with a low threshold intensity (0.20 mJ/cm2 at room temperature). This work demonstrates the realization of a plasmonic-waveguide nanolaser without the need for transfer and positioning steps, which is the key for on-chip integration of nanophotonic devices.

Solid-state perovskites have recently emerged as promising coherent light sources, due to their efficient gain. While the continuous-wave (CW) optically pumped perovskite laser has been achieved at low temperatures, the final frontier of an electrical perovskite-based laser diode remains challenging due to the heat management and intrinsic instability of perovskite materials. Here, we demonstrate waterproof perovskite-hexagonal boron nitride (hBN) hybrid nanolasers with low lasing thresholds and high operating temperature. After capping with the hBN flake, which possesses superb and anisotropic thermal conductivity, heat dissipation of the perovskite nanolaser is accelerated and an overheated hot spot is avoided. This results in the significant reduction of lasing thresholds (17.05% to 60.15%) in 16 measured samples and clear lasing behavior under a temperature as high as 75.6 °C. Moreover, hBN with high environmental stability can effectively protect the perovskite from the polar solvents. The hBN encaps...

This paper presents a comprehensive theoretical study of the optical and thermal properties of an electrically pumped semiconductor nanolaser (SNL) having an GaN/(InGaN/GaN MQWs)/GaN core shell structure. Numerical results show that the lasing whispering-gallery mode has a threshold gain of 413 cm $^{-1}$ . Furthermore, it is shown that when it is operated well-above threshold, the device temperature increases by only 22 K above an ambient temperature of 300 K. These promising results are attributed to the strong mode confinement in the active region and the good thermal properties of the material system of the proposed structure. The results presented in this paper offer guidelines for fabrication of electrically pumped room temperature continuous wave SNL operating in the visible spectral region.

Plasmonic nanolasers are a new class of laser device where surface plasmons are amplified by the stimulated emission in a plasmonic nanocavity. In contrast to conventional lasers, the physical size and the mode volume of plasmonic nanolasers can shrink beyond the optical diffraction limit. The strongly confined optical field leads to high performance of plasmonic nanolasers including ultrafast modulation speed and ultralow power consumption, while on another hand introduces challenges in characterizing their basic lasing properties. In this paper, we systematically characterize the lasing properties of plasmonic nanolasers in spatial, momentum, and frequency spaces simultaneously via leakage radiation microscopy and demonstrate a method to identify the exact lasing modes in a multimode plasmonic nanolaser. This paper advances the understanding of lasing emission behavior in plasmonic nanolasers and paves the way for intentionally manipulating their emission for various applications of on-chip nanophotonic circuits, nonlinear nanophotonics, sensing, and imaging.

Ideal integrated light emitters for optical interconnects should be compact in size, high in modulation bandwidth, efficient in energy consumption and tunable in frequency. Nanolasers are excellent candidates for such an application. In this article, we review and offer further in-depth analyses in three key aspects of recent nanolaser research, including second order intensity correlation, g 2 (τ) , characterizations, direct modulation and electromagnetic isolation in a dual nanolaser system. For coherence characterization, we review a technique exploiting not only the photon bunching peak, but also the g 2 (τ) pulse width to determine the spontaneous emission (SE), amplified SE and lasing regimes of a nanolaser with a high SE factor, β . We show that this technique is applicable for lasers with β ′s ranging from 10 −5 to unity. Additionally, we demonstrate the first direct current modulation of an electrically pumped metallo-dielectric nanolaser (MDNL) at 30 MHz. Considering the viability of nanolasers for dense integration, we then review the electromagnetic coupling between two closely spaced MDNLs and identify two practical methods to eliminate such coupling. Lastly, we review the state-of-the-art development in and offer future perspectives on three other important areas of nanolaser research ― integration with silicon photonics, wide-range frequency tuning and dual nanolaser dynamics.

Recent developments in small footprint plasmonic nanolasers show promise for active optical sensing with potential applications in various fields, including real-time and label-free biochemical sensing, and gas detection. In this study, we demonstrate a novel hybrid plasmonic crystal nanolaser that features a ZnO nanowire placed on Al grating surfaces with a nanotrench defect nanocavity. The lasing action of gain-assisted defect nanocavity overcomes the ohmic loss parasitically in the plasmonic nanostructures. Therefore, the plasmonic nanolaser exhibits an extremely small mode volume, a narrow linewidth Δλ, and a high Purcell factor that can facilitate the strong interaction between light and matter. This can be used as a refractive index sensor and is highly sensitive to local changes in the refractive indices of ambient materials. By careful design, the near-ultraviolet nanolaser sensors have significant sensing performances of glucose solutions, revealing a high sensitivity of 249 nm/RIU and high resol...

Controlling and generating coherent light fields in the nanoscale is critical for reducing the size of photonic circuitry. There are several demonstrations of zero-, one-, two-, and three-dimensional nanolaser architectures. Here we experimentally demonstrate a one-dimensional plasmonic laser, which consists of a periodic chain of aluminum nanoparticles and organic gain media. Lasing is observed at visible wavelengths, with clear thresholds and line widths down to 0.11 nm. Lasing occurs in a dark mode that extends over the whole structure, even outside the pumped area. The single lithography step fabrication and one-dimensional character allow for easy integration of these laser sources with other plasmonic structures.

Micro/nanoscale lasers that can deliver intense coherent light signals at (sub)wavelength scale have attracted great interest because of their promising applications ranging from on-chip information processing to high-throughput sensing. Compared with traditional inorganic materials, organic materials are ideal platforms to construct high performance microlasers, mainly because of their superiority in flexibly assembled structures for high-quality microcavities and abundant excited-state processes with large active cross sections for high gain emissions. This review begins with an overview of the research evolution of organic microlasers in terms of microcavity resonators and energy-level gain. Then a series of strategies to tailor the microcavity structures and excited-state dynamics of organic materials for the modulation of lasing performances are highlighted. Subsequently, we present the design and construction of organic-microlaser-based hybrid structures with advanced photonic functionalities. In the following part, we introduce their applications in chemical sensing, biosensing and integrated nanophotonics. Finally, we provide our outlook on the current challenges as well as the future direction of organic microlasers. It is anticipated that this review will provide inspiration for the development of miniaturized lasers with desired performances by tailoring of excited-state processes and microcavity structures toward practical applications.

Plasmonic nanolasers have attracted significant attention owing to their ability to generate a coherent optical field in the deep subwavelength region, and they exhibit promising applications in integrated photonics, bioimaging and sensing. However, the demonstration of lasing in individual metallic nanoparticles with 3D subwavelength confinement represents a significant challenge and is yet to be realized. Herein, we propose to mimic a plasmonic nanolaser via selective scattering off the evanescent tail of a lasing photonic nanobelt using a single silver nanorod (24 nm × 223 nm). The nanorod acts as an optical antenna that selectively extracts the near-field component along the rod axis. The light output from the silver nanorod mimics the emission of a plasmonic nanolaser in its localized near-field and polarization dependence, except for the lasing wavelength and linewidth, which are inherited from the photonic laser. The realization of localized coherent light sources provides promising nanoscale lighting that shows potential in background-suppressed illumination, biosensing and imaging.

Plasmonic nanolaser as a new type of ultra-small laser, has gain wide interests due to its breaking diffraction limit of light and fast carrier dynamics characters. Normally, the main problem that need to be solved for plasmonic nanolaser is high loss induced by optical and ohmic losses, which leads to the low quality factor. In this work, InGaN/GaN nanoplate plasmonic nanolaser with large interface area were designed and fabricated, where the overlap between SPs and excitons can be enhanced. The lasing threshold is calculated to be ~6.36 kW/cm2, where the full width at half maximum (FWHM) drops from 27 to 4 nm. And the fast decay time at 502 nm (sharp peak of stimulated lasing) is estimated to be 0.42 ns. Enhanced lasing characters are mainly attributed to the strong confinement of electromagnetic wave in the low refractive index material, which improve the near field coupling between SPs and excitons. Such plasmonic laser should be useful in data storage applications, biological application, light communication, especially for optoelectronic devices integrated into a system on a chip.

In this work, we demonstrated the formation of nonuniform two-dimensional electron gases (2DEGs) with visible surface plasmon polaritons' (SPPs) supportiveness in un- and ZnSe-coated Nd3+ doped (Pb,La)(Zr,Ti)O3 ceramics (Nd:PLZT), and its enhancement effect on random lasing and weak localization of light. Firstly, charge density distribution in the modified ZnSe film was calculated, revealing the formation of nonuniform 2DEGs, namely, a very thin metallized layer. In bulk samples, the excitation of SPPs contributes to the transformation from conventional lasing to random lasing, as evidenced by the dynamics. The optical whisper-gallery-like pattern was observed in a cylinder shaped Nd:PLZT, demonstrating convincingly SPPs propagating along the border owing to the polarity discontinuity. Based on this, Nd:PLZT was processed into powdered forms to increase the surface-volume ratio. Furthermore, the powdered specimen was coated with ZnSe film to further strengthen plasmonic impact. A 7.6 × enhancement in random lasing at 589 nm and three-fold reduction in threshold of weak localization of light at 684 nm were observed in the ZnSe/Nd:PLZT, by comparing to the bare Nd:PLZT. This work opens an avenue leading to SPPs’ implementation without any metal parts involved and hence presents a promising candidate for serving as nanolaser for nanophotonic circuits.