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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.

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.

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.

Cataloged from PDF version of article. Thesis (M.S.): Bilkent University, Department of Materials Science and Nanotechnology, İhsan Doğramacı Bilkent University, 2021. Includes bibliographical references (leaves 43-48). Vertical-cavity surface-emitting lasers (VCSEL) are the ideal light sources for optical data communication and 3D sensing due to their small size, low power consumption, high-speed modulation, and low cost. The key to meeting the ever-increasing demand for higher efficiency and modulation devices is scaling down the cavities to near- or sub-wavelength sizes. The current state-of-the-art commercial oxide-VCSEL technology has been very successful for micro-scale cavity diameters (>3 µm), but its processing approach is not appropriate for further miniatur-ization. Improvement in the performance of oxide-VCSELs can be achieved with smaller oxide aperture diameters. However, the high thermal resistance induced by the oxide layer significantly degrades the device performance, especially for the smaller sizes, making this method unreliable for scaling. In this work, we investigated a lithographically defined VCSEL (Li-VCSEL) method in which the transverse photonic and electrical confinement can be enabled by epitaxial growth and lithography. Transverse optical confinement is achieved by introducing an intracavity phase-shifting mesa that provides the confinement by index guiding. Numerical simulation results show high-quality factors even for submicron sizes, which is promising for the realization of submicron size single emitter and high-density array lasers. The fabrication steps include the epitaxial growth of the bottom semiconductor DBR and the cavity, defining the phase-shifting mesa us-ing optical lithographic processes, and the deposition of the top dielectric DBR using thin film deposition techniques. We demonstrated room-temperature lasing around 980 nm from Li-VCSELs with mesa diameters ranging from 0.75 µm to 2.0 µm under continuous-wave optical pumping and presented detailed charac-terization of these devices. The results represent a significant step towards the realization of electrically pumped small-size lasers for practical optoelectronics applications. by Abdulmalik Abdulkadir Madigawa M.S.

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.

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.

A novel perovskite hybrid surface plasmon waveguide structure is designed. Established its physical model and introduced its theoretical basis in detail. Based on the finite element method, the mode characteristics, quality factor, and gain threshold of the waveguide structure are analyzed with geometric parameters. The results show that the optical field constraint of the waveguide can reach a good deep sub-wavelength level under the optimal operating wavelength of 1550nm. By adjusting the waveguide design parameters, the high quality factor, low energy loss, low threshold limit and ultra small effective mode field area are obtained. Compared with the hybrid waveguide structure proposed in the current research results, this structure has stronger optical field limiting ability and microcavity binding ability. The waveguide structure can provide theoretical and technical support for the development of new efficient nano laser devices, and has a good application prospect.

Optical devices can beyond the diffraction limit through surface plasmon technology and realize on-chip optical interconnection. A qualified on-chip light source needs to meet the following requirements: smaller size, lower power consumption and higher output power. In our study, a nanolaser is designed based on surface plasmon, and a 1D photonic crystal structure is combined with the etching periodic and taper holes in the transverse waveguide. We simulated the Q factor, Purcell factor, mode volume, and waveguide coupling efficiency of resonantor, and analyzed the output characteristics and modulation response characteristics of the laser. Studies have shown that the combo surface plasmon 1D photonic crystal nanobeam cavity has excellent performance, the mode volume is only 0.15 (λ R /n)3, and the Q factor of 808, the Purcell factor of 106 and the waveguide coupling efficiency of 75% are achieved. The nanolaser we designed works at a wavelength of 1535nm, with a 3-dB bandwidth at a threshold pump rate of 134GHz, and produces an output power of more than 10μW at an injection current of 17μA, which meets the energy requirements of the nanometre chip light source. This ultra-small nanometre light source with low power consumption and high modulation rate provides a new solution for the next generation of on-chip optical interconnection.

We theoretically demonstrated a kind of plasmon coupled elliptical nanostructure to achieve a vast range of applications based on nanolaser or spaser with high intensity. To overcome the ohmic losses, the plasmon ellipse is composed of the gold film substrate with a gain media. A simple ellipse has been chosen from which variety of dimer configurations have been formed by symmetry alteration technique which are then tested for different light polarizations and gap variations. The proposed model supports localized surface plasmon resonance mode (LSPR). Moreover, the localized surface plasmon resonance (LSPR) property of the proposed nanostructure is numerically analysed by the finite-element method (FEM) and the results shows that the electric field intensity (EFI) can be amplified to a large values by symmetry breaking in the elliptical nanostructure. Various plasmon modes can be excited by selecting the appropriate gain media. In addition to this, a compact tunable multi-wavelength nanolaser (spaser) can be developed by using this model. Giant near field enhancement (NFE) and high LSPR enable this structure to be promising for spaser applications such as surface enhanced Raman spectroscopy, sensing, lithography, imaging, dental applications and much more.

Photonic crystal cavities enable strong light–matter interactions, with numerous applications, such as ultra-small and energy-efficient semiconductor lasers, enhanced nonlinearities and single-photon sources. This paper reviews the properties of the modes of photonic crystal cavities, with a special focus on line-defect cavities. In particular, it is shown how the fundamental resonant mode in line-defect cavities gradually turns from Fabry–Perot-like to distributed-feedback-like with increasing cavity size. This peculiar behavior is directly traced back to the properties of the guided Bloch modes. Photonic crystal cavities based on Fano interference are also covered. This type of cavity is realized through coupling of a line-defect waveguide with an adjacent nanocavity, with applications to Fano lasers and optical switches. Finally, emerging cavities for extreme dielectric confinement are covered. These cavities promise extremely strong light–matter interactions by realizing deep sub-wavelength mode size while keeping a high quality factor.

An optical analogue of magic-angle twisted graphene bilayer gives rise to rigorously stopped light, which coupled with gain allows for a new type of a nanolaser with remarkable figures of merit.

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.

The development of compact and energy-efficient miniaturised lasers is a critical challenge in integrated non-linear photonics. Current research focuses on the integration of subwavelength all-dielectric lasers in CMOS compatible platforms. These systems provide a viable alternative to state-of-the-art nanoplasmonic sources, whose practicality is often hindered by high metal losses. The efficiency of dielectric nanolasers, however, is affected by the diffraction limit of light, which restricts the degree of localisation achievable with standard resonator modes. The recent development of new types of radiationless states has brought a sharp innovation in the field of subwavelength dielectric lasers. Radiationless states are exotic electromagnetic solutions that originate from the complex superposition and interaction of several resonator modes. They are associated with a high degree of near-field localisation which makes them particularly advantageous for non-linear photonics applications. In this work, we provide an overview of the most recent theoretical and experimental efforts toward the development of integrated lasers and ultrafast sources based on the amplification of exotic radiationless states. In particular, we focus our attention on two specific types of radiationless states: optical anapoles and Bound States in the Continuum (BIC). By discussing their differences and similarities, we provide a unifying view of these distinct research areas and outline possible future directions for these innovative platforms.

The plasmonic nanolaser is a class of lasers with the physical dimensions free from the optical diffraction limit. In the past decade, progress in performance, applications, and mechanisms of plasmonic nanolasers has increased dramatically. We review this advance and offer our prospectives on the remaining challenges ahead, concentrating on the integration with nanochips. In particular, we focus on the qualifications for electrical pumping, energy consumption, and ultrafast modulation. At last, we evaluate the strategies for on-chip source construction design and further threshold reduction to achieve a long-term room-temperature electrically pumped plasmonic nanolaser, the ultimate goal toward practical applications.

A history and a glimpse into the future of spaser (acronym for “surface plasmon amplification by stimulated emission of radiation”) is provided. The spaser (also called a plasmonic nanolaser) is an active nanosystem including a gain medium and a nanoplasmonic metal core. It generates coherent intense nanolocalized fields. Theoretically predicted in 2003 by Bergman and Stockman, the spaser grew into a large fundamental research and application field with thousands of publications. We review a few of them to illustrate the most important and general fundamental properties of the spaser. We also review some selected applications of spasers, in particular, to ultrasensing and biomedical problems, concentrating on cancer-cell theranostics (therapeutics and diagnostics). In conclusion, we attempt to glimpse into the future by predicting that the next big development of the spasers will be topological nano-optics, and its “killer” application will be ultrafast, high-density on-chip communications for future information processing.

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

To realize ubiquitously used photonic integrated circuits, on-chip nanoscale sources are essential components. Subwavelength nanolasers, especially those based on a metal-clad design, already possess many desirable attributes for an on-chip source such as low thresholds, room-temperature operation and ultra-small footprints accompanied by electromagnetic isolation at pitch sizes down to ∼50 nm. Another valuable characteristic for a source would be control over its emission wavelength and intensity in real-time. Most efforts on tuning/modulation thus far report static changes based on irreversible techniques not suited for high-speed operation. In this study, we demonstrate in-situ dynamical tuning of the emission wavelength of a metallo-dielectric nanolaser at room temperature by applying an external DC electric field. Using an AC electric field, we show that it is also possible to modulate the output intensity of the nanolaser at high speeds. The nanolaser’s emission wavelength in the telecom band can be altered by as much as 8.35 nm with a tuning sensitivity of ∼1.01 nm/V. Additionally, the output intensity can be attenuated by up to 89%, a contrast sufficient for digital data communication purposes. Finally, we achieve an intensity modulation speed up to 400 MHz, limited only by the photodetector bandwidth used in this study, which underlines the capability of high-speed operation via this method. This is the first demonstration of a telecom band nanolaser source with dynamic spectral tuning and intensity modulation based on an external E-field to the best of our knowledge.

A large number of studies have been carried out to understand the nonlinear dynamics of nanolasers, yet there is a lack of comprehensive consideration on the optimization of chaotic output and its application to chaos secure communications. In this paper, we used an optically injected nanolaser structure to generate broadband chaos without a time-delay signature (TDS), which acts as the chaotic carrier in the proposed communication scheme. Due to the combination of desired TDS suppression enabled by the nanolasers and a two-channel transmission technique, the proposed scheme offers enhanced security for message encryption and decryption. We also considered the influence of some key parameters on the TDS suppression and that of parameter mismatch on chaos synchronization and message recovery. The detailed studies indicate that the proposed nanolaser-based scheme offers satisfactory TDS suppression performance over a wide range of parameters considered and is robust to resist fabrication imperfections-induced mismatch under proper injection conditions.

A reflectivity-enhanced hybrid plasmonic GaAs/AlGaAs core-shell nanowire laser is proposed and studied by 3D finite-difference time-domain simulations. The results demonstrate that by introducing thin metal mirrors at both ends, the end facet reflectivity of nanowire is increased by 30&ndash, 140%, resulting in a much stronger optical feedback. Due to the enhanced interaction between the surface charge oscillation and light, the electric field intensity inside the dielectric gap layer increases, resulting in a much lower threshold gain. For a small diameter in the range of 100&ndash, 150 nm, the threshold gain is significantly reduced to 60&ndash, 80% that of nanowire without mirrors. Moreover, as the mode energy is mainly concentrated in the gap between the nanowire and metal substrate, the output power maintains &gt, 60% that of nanowire without mirrors in the diameter range of 100&ndash, 150 nm. The low-threshold miniaturized plasmonic nanowire laser with simple processing technology is promising for low-consumption ultra-compact optoelectronic integrated circuits and on-chip communications.

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.