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Nothotsuga is a monotypic genus of Pinaceae endemic to southern China today. Molecular data indicate that Nothotsuga split from Tsuga during the Palaeogene with the earliest fossils from the upper ...

A single quantum dot (QD) strongly coupled with a plasmonic nanoparticle yields a promising qubit for scalable solid-state quantum information processing at room temperature. However, realizing such a strong coupling remains challenging due to the difficulty of spatial overlap of the QD excitons with the plasmonic electric fields (EFs). Here, by using a transmission electron microscope we demonstrate for the first time that this overlap can be realized by integrating a deterministic single QD with a single Au nanorod. When a wedge nanogap cavity consisting of them and the substrate is constructed, the plasmonic EFs can be more effectively "dragged" and highly confined in the QD's nanoshell where the excitons mainly reside. With these advantages, we observed the largest spectral Rabi splitting (reported so far) of ∼234 meV for a single QD strong coupling with plasmons. Our work opens a pathway to the massive construction of room-temperature strong coupling solid qubits.

It can solve the disadvantages of traditional crop biochemical parameters measurement methods on combining hyperspectral technology with machine learning technology to retrieve crop growth index. Four nitrogen application levels were set by taking rice varieties Zhuliangyou 819 and Zhuliangyou 39 as materials. Through the rice test in 2020, the spectral data of rice leaves at different growth stages and their corresponding SPAD values and nitrogen contents were collected. Savitzky-Golay Smoothing (SG), Standard Normal Variable (SNV), Principal Component Analysis (PCA) and Multiplicative Scattering Correction (MSC) were used to preprocess spectral reflectance. Three classifiers, Support Vector Machine (SVM), Partial Least Squares Regression (PLSR) and Random Forest (RF) were used to build the model. The results showed that SG-PLSR combination had the highest accuracy in predicting chlorophyll and nitrogen in double-cropping rice. The test results provide a good reference for other indexes of rice.

Employing nanostructure to generate large chiroptical response has been cultivated as an emerging field, for its great potentials in integrated optics, biochemistry detections, etc. However, the lack of intuitive approaches for analytically describing the chiroptical nanoparticles has discouraged researchers from effectively designing advanced chiroptical structures. In this work, we take the twisted nanorod dimer system as a basic example to provide an analytical approach from the perspective of mode coupling, including far-field coupling and near-field coupling of nanoparticles. Using this approach, we can calculate the expression of circular dichroism (CD) in the twisted nanorod dimer system, which can establish the analytical relationship between the chiroptical response and the basic parameters of this system. Our results show that the CD response can be engineered by modulating the structure parameters, and a high CD response of ∼ 0.78 under the guidance of this approach has been achieved.

Ordered assemblies of individual metal nanoparticle building blocks have been important platforms in exploring plasmon-based light–matter interactions. Despite the fact that such assemblies have be...

Plasmons, the electromagnetic excitations coupled with electron waves, possess the intrinsic ability of manipulating light at subwavelength scales down to picometer. This ability not only helps uncovering the fascinating quantum behaviors that strengthen the basic understanding of quantum science, but also enables the inventions of various quantum optoelectronic devices, triggering the birth of quantum plasmonic technology. The past decade has witnessed the flourishing of this technology. In this review, we first focus on fundamental investigations into quantum behaviors for both “isolated” plasmonic nanostructures and “coupled” plasmon-emitter systems, emphasizing new theoretical frameworks and experimental advances. Leveraging on these fundamentals, the progress in exploring and applying quantum plasmonic devices is discussed, such as quantum plasmonic circuits, nanolasers, biochemistry, and spin-orbit interaction devices. Upon summarizing the past and present developments, the future research directions and promising applications are highlighted.

Integrated photonic circuits with quantum dots provide a promising route for scalable quantum chips with highly efficient photonic sources. However, unpolarized emission photons in general sacrifice half efficiency when coupling to the waveguide fundamental mode by a cross polarization technique for suppressing the excitation laser, while suspended waveguide photonics sources without polarization filters have poor scalability due to their mechanical fragility. Here, we propose a strategy for overcoming the challenge by coupling an elliptical Bragg resonator with waveguides on a solid-state base, featuring near-unity polarization efficiency and enabling on-chip pulsed resonant excitation without any polarization filters. We theoretically demonstrate that the proposed devices have outstanding performance of a single-photon source with 80% coupling efficiency into on-chip planar waveguides and an ultra-small extinction ratio of 10 − 11 , as well as robustness against quantum dot position deviation. Our design provides a promising method for scalable quantum chips with a filter-free high-efficiency single-photon source.

Full-field optical angiography is critical for vascular disease research and clinical diagnosis. Existing methods struggle to improve the temporal and spatial resolutions simultaneously.Spatiotemporal absorption fluctuation imaging (ST-AFI) is proposed to achieve dynamic blood flow imaging with high spatial and temporal resolutions.ST-AFI is a dynamic optical angiography based on a low-coherence imaging system and U-Net. The system was used to acquire a series of dynamic red blood cell (RBC) signals and static background tissue signals, and U-Net is used to predict optical absorption properties and spatiotemporal fluctuation information. U-Net was generally used in two-dimensional blood flow segmentation as an image processing algorithm for biomedical imaging. In the proposed approach, the network simultaneously analyzes the spatial absorption coefficient differences and the temporal dynamic absorption fluctuation.The spatial resolution of ST-AFI is up to 4.33 μm, and the temporal resolution is up to 0.032 s. In vivo experiments on 2.5-day-old chicken embryos were conducted. The results demonstrate that intermittent RBCs flow in capillaries can be resolved, and the blood vessels without blood flow can be suppressed.Using ST-AFI to achieve convolutional neural network (CNN)-based dynamic angiography is a novel approach that may be useful for several clinical applications. Owing to their strong feature extraction ability, CNNs exhibit the potential to be expanded to other blood flow imaging methods for the prediction of the spatiotemporal optical properties with improved temporal and spatial resolutions.

Strong coupling between quantum emitters and photonic modes, at which the level splitting (LS) of the mixed quantum states occurs, has aroused great interest due to diverse important quantum applications. The spectral Rabi-splitting (SRS) in photon emission or absorption has been extensively used to characterize strong coupling based on the equality assumption by assigning the SRS to LS. Here, we demonstrate that the equality assumption is usually invalid via a unified quantum treatment on the coupled plasmon-exciton system. It is revealed that the strong coupling characterized by the SRS is easily observed from the subsystem with larger decay, manifesting itself in relativity and diversity, which is highly correlated to the dissipative decays of the coupling subsystems. The plasmon-exciton interactions can be classified into the weak coupling, pseudo-, dark-, intermediate- and super-strong coupling regimes. Our work not only enriches the underlying physics of strong light-matter interactions, but also may stimulate further experimental researches in this field.

The generation and manipulation of single photons are crucial in advanced quantum technologies, such as quantum communication and quantum computation devices. High-purity single photons can be generated from classical light using the single-photon blockade (1PB). However, the efficiency and purity are exclusive in 1PB, which hinders its practical applications. Here, we show that the resonantly coupled plasmonic-photonic cavity can boost the efficiency of single-photon generation by more than three orders of magnitude compared with that of all-dielectric microcavity. This significant improvement is attributed to two new mechanisms of atom-microcavity coupling after introducing the plasmonic cavity: the formation of a quasi-bound state and the transition to the nonreciprocal regime, due to the destructive interference between the coupling pathways and the nonzero relative phase of the closed-loop coupling, respectively. The quasi-bound state has a relatively small decaying, while its effective coupling strength is significantly enhanced. Suppressing the dissipative component of the effective atom-microcavity coupling in the nonreciprocal regime can further improve single-photon performance, particularly without temporal oscillations. Our study demonstrates the possibility of enhancing the intrinsically low efficiency of 1PB in low excitation regime, and unveils the novel light-matter interaction in hybrid cavities.

Single-exciton strong coupling with plasmons is highly desirable for exploiting room-temperature quantum devices and applications. However, the large plasmon decay makes the realization of such strong coupling extremely difficult. To overcome this challenge, here we propose an effective approach to easily achieve the single-exciton strong coupling at room temperature by controlling quantum exceptional point (QEP) of the coupling system via matching the decay between the localized plasmon mode (LPM) and exciton. The good match can be reached by suppressing the LPM’s decay with the use of a leaky Fabry-Perot cavity. Experimental results show that the LPM’s decay linewidth is greatly compressed from ~ 45 nm to ~ 15 nm, which is close to the excitonic linewidth (~ 10 nm), pushing their interaction from the Fano interference into the strong coupling. Our work opens a new way to flexibly control the QEP and more easily realize the single-exciton strong coupling in ambient conditions.

High-performance solid-state quantum sources in the telecom band are of paramount importance for long-distance quantum communications and the quantum Internet by taking advantage of a low-loss optical fiber network. Here, we demonstrate bright telecom-wavelength single-photon sources based on In(Ga)As/GaAs quantum dots (QDs) deterministically coupled to hybrid circular Bragg resonators (h-CBRs) by using a wide-field fluorescence imaging technique. The QD emissions are redshifted toward the telecom O-band by using an ultra-low InAs growth rate and an InGaAs strain reducing layer. Single-photon emissions under both continuous wave (CW) and pulsed operations are demonstrated, showing high brightness with count rates of 1.14 MHz and 0.34 MHz under saturation powers and single-photon purities of g ( 2 ) ( 0 ) = 0.11 ± 0.02 (CW) and g ( 2 ) ( 0 ) = 0.087 ± 0.003 (pulsed) at low excitation powers. A Purcell factor of 4.2 with a collection efficiency of 11.2 % ± 1 % at the first lens is extracted, suggesting efficient coupling between the QD and h-CBR. Our work contributes to the development of highly efficient single-photon sources in the telecom band for fiber-based quantum communication and future distributed quantum networks.

Background To investigate the relationships of monocyte to high-density lipoprotein cholesterol (HDL-C) ratio (MHR) with left ventricular hypertrophy (LVH) in young and middle-aged patients with essential hypertension (EH). Methods A retrospective analysis was performed on clinical data of 294 young and middle-aged patients with EH (aged from 18 to 65 years old). According to the left ventricular mass index (LVMI), the patients were divided into LVH (n = 98) and non-LVH (n = 196) groups. The data on echocardiography, routine blood test, biochemical examination, and so on were collected in all subjects, then LVMI and MHR were calculated. The association between MHR and hypertensive LVH was analyzed by correlation and binary logistic regression analyses. The receiver operating characteristic curve (ROC) was used to determine the predict value of MHR. Results MHR was higher while HDL-C was lower in the LVH group compared with the non-LVH group (MHR: 0.47 ± 0.11 vs. 0.33 ± 0.12, P < 0.001; HDL-C: 1.05 [0.94–1.22] vs. 1.27 [1.07–1.47] mmol/l, P < 0.001). Correlation analysis showed that LVMI was positively correlated with MHR (r = 0.381, P < 0.001). Multivariate logistic regression analysis showed that MHR was an independent risk factor for LVH in young and middle-aged EH patients (odds ratio = 2.914, 95% confidence interval [CI] 2.084–4.068, P < 0.001) after adjusting for body mass index, smoking, HDL-C, and other confounding factors. The area under the ROC curve of MHR for predict LVH was 0.831 (95% CI 0.782–0.880), and the optimal cutoff value of MHR was 0.37, with a sensitivity of 93.9% and a specificity of 75.5%. Conclusions MHR is positively correlated with LVH in young and middle-aged patients with EH. MHR is an independent risk factor for LVH in this population, and can be used for LVH risk screening.

We first investigate the nondipole effect of asymmetric quantum dots (QDs) in plasmonic antennas of shell, rod, triangle, and disk. The rod and triangle are found to have greater nondipole effect compared to shell and disk due to the larger electric field gradients resulting from high surface curvature. For a 3nm-radius QD adjacent to the rod end or the corner of triangle, the coupling strength of plasmon-QD interaction has a 10% enhancement for dipolar plasmonic mode. The multipole expansion shows that the enhancement is mainly contributed by the dipole-quadrupole transition interference, which will be suppressed in a symmetrical dimer structure. We further explore the nondipole effect in the plasmonic nanocavity formed by a gold nanotip and substrate. The nondipole effect is found to increase the quantum nonlinearities and lead to better single-photon purity. Our work demonstrates the impact of nondipole effect on plasmon-QD strong coupling and potential applications in quantum optics.

The integration of single-photon sources and metasurfaces provides powerful conceptual structures for quantum optics applications., The semiconductor quantum dot (QD) has been successfully demonstrated as a potentially scalable and on-chip integration technology to generate the triggered photon streams that have many important applications in quantum information science. However, the randomicity of these photon streams emitted from the QD seriously compromises its use and especially hinders the on-demand manipulation of the spin states. Here, by accurately integrating a QD and its mirror image onto the two foci of a bifocal metalens, we demonstrate the on-demand generation and separation of the spin states of the emitted single photons. The photon streams with different spin states emitted from the QD can be flexibly manipulated to propagate along arbitrarily designed directions with high collimation of the smallest measured beaming divergence angle of 3.17°. Our work presents an effectively integrated quantum method for the simultaneously on-demand manipulation of the polarization, propagation, and collimation of the emitted photon streams.

Photons that have a helical phase front, that is, twisted photons, can carry a discrete, in principle, unlimited, but quantized amount of orbital angular momentum (OAM). Hence, twisted single photons constitute a high-dimensional quantum system with information-processing abilities beyond those of two-level single-photon qubits. To date, the generation of single photons carrying OAM has relied on a non-linear process in bulk crystals, for example, spontaneous parametric down-conversion, which limits both the efficiency and the scalability of the source. Here, we present a bright solid-state source of single photons in an OAM superposition state with a single-photon purity of g(2)(0) = 0.115(1) and a collection efficiency of 23(4)%. The mode purity of the single-photon OAM states is further examined via projection measurements. Future developments of integrated quantum photonic devices with pure OAM states as an additional degree of freedom may enable high-dimensional quantum information processing. Single photons with high orbital angular momenta can act as higher order flying qubits, but efficient generation is scarce. The integration of a single quantum dot emitter into an on-chip mircoring resonator enables the generation of single photons in an orbital angular momentum superposition state.

Generation of multi-photon entangled states with high efficiency in integrated photonic quantum systems is still a big challenge. The usual three-photon generation efficiency based on the third-order nonlinear effect is extremely low. Here, we propose a scheme to generate three-photon correlated states, which are entangled states in frequency space and bound states in real space, with high efficiency. This method relies on two crucial processes. On one hand, by employing a Sagnac interferometer, an incident photon can be transformed into a symmetric superposition of the clockwise and counterclockwise modes of the Sagnac loop, which can then be perfectly absorbed by the emitter. On the other hand, the coupling strengths of the two transition paths of the emitter to the Sagnac loop are set to be equal, under which the absorbed photon can be emitted completely from the cascaded transition path due to quantum interference. By adjusting the coupling strengths among the three transition paths of the emitter and the waveguide modes, we can control the spectral entanglement and spatial separation among the three photons. Our proposal can be used to generate three-photon entangled states on demand, and the efficiency can be higher than 90% with some practical parameters, which can find important applications in integrated quantum information processing.

Perovskite lasers have aroused great interest in recent years due to their ultra-low lasing threshold, high quantum yields, easily tuned emission colors and great potential for electrically pumped nanolasing, which opens up new possibilities in obtaining highly coherent light sources at the nanoscale. Compared with the widely studied organic-inorganic hybrid perovskites, the inorganic (CsPbX3) have gradually become an emerging research focus because of their relatively better stability. However, some problems still hinder their actual applications, such as the seldom explored lasing quantum yield and the difficulties of further improving stability. Herein, a simple method is proposed to synthesize CsPbX3 nanowires in ambient conditions, and these CsPbX3 nanowires exhibit perfect crystallization and outstanding stability (over 1 year). Perovskite lasing with single mode and a low threshold of 12.33 μJ cm-2 as well as a high lasing quantum yield up to ∼58% are obtained. More interestingly, a high quality single-mode laser with ultra-narrow linewidth of 0.09 nm can be obtained when the CsPbX3 NWs are excited by continuous wave in low-temperature condition. Our results not only enrich the study of inorganic perovskite materials with a new synthetic method, but also uncover new lasing properties of CsPbX3 NWs, suggesting a broad application of the inorganic perovskite materials.

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

Dielectric metasurfaces require high refractive index contrast materials for optimum performance. This requirement imposes a severe restraint; devices have either been demonstrated at wavelengths of 700nm and above using high-index semiconductors such as silicon, or they use lower index dielectric materials such as TiO$_{2}$ or Si$_{3}$N$_{4}$ and operate in the visible wavelength regime. Here, we show that the high refractive index of silicon can be exploited at wavelengths as short as 532 nm by demonstrating a silicon metasurface with a transmission efficiency of 47% at this wavelength. The metasurface consists of a graded array of silicon posts arranged in a square lattice on a quartz substrate. We show full 2�� phase control and we experimentally demonstrate polarization-independent beam deflection at 532nm wavelength. The crystalline silicon is placed on a quartz substrate by a bespoke layer transfer technique and we note that an efficiency >70% may be achieved for a further optimized structure in the same material. Our results open a new way for realizing efficient metasurfaces based on silicon in the visible wavelength regime., 16 pages, 6 figures, 2 tables

The colour gamut, a two-dimensional (2D) colour space primarily comprising hue and saturation (HS), lays the most important foundation for the colour display and printing industries. Recently, the metasurface has been considered a promising paradigm for nanoprinting and holographic imaging, demonstrating a subwavelength image resolution, a flat profile, high durability, and multi-functionalities. Much effort has been devoted to broaden the 2D HS plane, also known as the CIE map. However, the brightness (B), as the carrier of chiaroscuro information, has long been neglected in metasurface-based nanoprinting or holograms due to the challenge in realising arbitrary and simultaneous control of full-colour HSB tuning in a passive device. Here, we report a dielectric metasurface made of crystal silicon nanoblocks, which achieves not only tailorable coverage of the primary colours red, green and blue (RGB) but also intensity control of the individual colours. The colour gamut is hence extruded from the 2D CIE to a complete 3D HSB space. Moreover, thanks to the independent control of the RGB intensity and phase, we further show that a single-layer silicon metasurface could simultaneously exhibit arbitrary HSB colour nanoprinting and a full-colour hologram image. Our findings open up possibilities for high-resolution and high-fidelity optical security devices as well as advanced cryptographic approaches., Synchronous Nanoprinting-Hologram Metasurfaces: Towards full hue-saturation-brightness control Structural colours with hue-saturation-brightness (HSB) control and independent integration with full-colour hologram open up possibilities for optical security devices and advanced cryptographic approaches. Researchers from China and Singapore propose a crystalline-silicon nanoblock metasurface that is able to control the intensity and phase of transmitted red, green, blue (RGB) lights independently. By mixing the three RGB nanoblocks with different intensity proportions together, it is possible to control the HSB value of the transmitted light, pushing the metasurface structural colour from conventional two-dimensional hue-saturation space to a real three-dimensional HSB space. Furthermore, arbitrary HSB colour printing and full-colour hologram images can be integrated in one single metasurface structure. That makes a drastic leap for singlet multifunctional metasurfaces, instead of cascading multiple metasurfaces with one for colourprinting and the other for hologram respectively.

Solid-state quantum electrodynamics (QED) not only demonstrates basic principles of quantum physics, but also provides key support to future quantum technologies. However, the non-modifiability of the fabricated solid-state QED systems limits their flexibility and versatility in manipulating light-matter interaction, and severely hinders their practical applications. Here, we put forward an approach of multi-dimensionally manipulating light-matter interaction to realize a dynamically tunable multifunctional QED platform by combining the local light-induced refractive index modulation (LRIM) and strong dispersion characteristic of the photonic crystal (PC) waveguide. We demonstrate three significant functions of the platform as examples: switch control between weak and strong couplings on demand, distant quantum entanglement, and a directional single photon source with high brightness and efficiency. These functions are strongly robust against positioning error of the quantum emitter, and can be facilely realized only by local LRIM on one PC waveguide. Our work paves a new way for the realization of multifunctional quantum devices.

Photonic nanostructures with resonant modes that can generate large electric field (EF) enhancements are applied to enhance light-matter interactions in nanoscale, bringing about great advances in both fundamental and applied science. However, a small hot spot (i.e., the regions with strong EF enhancements) and highly inhomogeneous EF distribution of the resonant modes usually hinder the enhancements of light-matter interactions in a large spatial scale. Additionally, it is a severe challenge to simultaneously generate multiple resonant modes with strong EF enhancements in a broadband spectral range, which greatly limits the capacity of a photonic nanostructure in boosting optical responses including nonlinear conversion, photoluminescence, etc. In order to overcome these challenges, we presented an arrayed hyperbolic metamaterial (AHMM). This AHMM structure is applied to simultaneously enhance the three-photon and four-photon luminescence of upconversion nanoparticles. Excitingly, the enhancement of the three-photon process is 1 order of magnitude larger than previous records, and for the enhancing four-photon process, we achieve an enhancement of 3350 times, greatly beneficial for overcoming the crucial problem of low efficiency in near infrared light upconversion. Our results demonstrated a promising platform for realizing giant enhancements of light-matter interactions, holding potential in constructing various photonics applications such as the nonlinear light sources.

We investigate optical second harmonic generation (SHG) from individual self-catalyzed zinc-blende (ZB) GaAs nanowires (NWs), where the polarimetry strongly depends on the NW diameter. We report a direct observation on the SHG induced by surface nonlinear susceptibilities in a single, ultra-thin GaAs NW. By considering the contributions from both optical field and structural discontinuities in our theoretical model, we can well explain the optical SHG polarimetry from NWs with different diameters. We also show that the optical in-coupling coefficient arising from the depolarization electromagnetic field can determine the polarization of the SHG. The results open perspectives for further geometry-based studies on the origin and control of SHG in small nanostructures.

Nanowire quantum dots (NW-QDs) can be used for future compact and efficient optoelectronic devices. Many efforts have been made to control the QD states by inserting the QDs in doped structures and applying an electric field in a nanowire system. In this paper, we use down-conversion and up-conversion photoluminescence excitations to explore the optical and electronic properties of single quantum dots in GaAs/AlGaAs core-shell nanowires. We investigate a large optical Stark shift in this system as a new method to tune the QD states. When the tunable laser lies within the spectral bandwidth of ZB/WZ GaAs (780 nm-860 nm), we observe an extremely large optical Stark shift of 1.3 nm (0.5 nm) with increasing excitation power at a resonant wavelength of 800 nm (840 nm) in GaAs states. The ability to in situ control the energy states of self-catalyzed NW-QDs should open a new way for quantum light sources and nonlinear optics in a nanowire system.

We extend and optimize the axisymmetric 2.5-D eigensolver to calculate the far-field results of axisymmetric structures in stratified backgrounds (SBs), which is useful and practical for optical design and engineering. Two kinds of near-field-to-far-field transformations (NFFFTs) are proposed. One is called closed-surface transformation which is based on the dipole radiations in SBs. The other is called open-surface transformation which is based on the analytic continuation. This transformation can provide the far-field results of any axisymmetric structure (including backgrounds). The far-field results achieved by these two transformations are in good agreement with each other and with analytical ones. Moreover, in order to obtain accurate near-field results, we optimize the perfectly matched layer (PML) setting of the 2.5-D eigensolver. Corresponding optimization rules are proposed and discussed.

Employing a silver nano semi-ellipsoid nanoarray with high symmetry into applications in plasmonic color printing, we fulfill printing images with colors independent of observing angles. Also, by decreasing the period of a nano semi-ellipsoid array into deep-subwavelength scales, we obtain high reflectivity over 50%, promising high efficiency for imaging generations. A facile technique based on the transfer of anodized aluminum oxide template is developed to fabricate the silver nano semi-ellipsoid nanoarray, realizing plasmonic color printing with features of low cost, scalable, full color and high flexibility. Our approach provides a feasible way to address the angle-dependent issue in the previous practice of plasmonic color printing, and boosts this field on its way to real-world commercial applications.

The electronic, magnetic properties and optical absorption of vanadium (V) doped rutile TiO2 have been studied by the generalized gradient approximation GGA and GGA+U (Hubbard coefficient) approach respectively. On the one hand, we consider the influence of vanadium with different doping concentration on the electronic structure. On the other hand, we study double V atoms doped TiO2, mainly study four V-doped TiO2 configurations, and find the magnetic ground states are ferromagnetic state. For the TiO2@V-V1, TiO2@V-V3 and TiO2@V-V4 configurations without O ion as bridge between V-V atoms, there will have a metastable state of antiferromagnetic configurations, while, for the TiO2@V-V2 configurations with an O ion as bridge between V-V atoms, due to the existence of superexchange between V-O-V, there will only exist the ground state of ferromagnetic state and there are no other metastable configurations. Furthermore, the optical properties of V-doped TiO2 are calculated. The results show that the V-doped TiO2 has strong infrared light absorption and visible light absorption.

Light-matter interaction in the strong coupling regime enables light control at the single-photon level. We develop numerical method and analytical expressions to calculate the decay kinetics of an initially excited two-level quantum emitter in dielectric nanostructure and single-mode cavity, respectively. We use these methods to discover the dual effects of disorder on the strongly-coupled system composed of a single quantum dot and a photonic crystal L3 cavity. The quality factor is sensitive to disorder, while the g factor and vacuum Rabi splitting are robust against disorder. A small amount of disorder may either decrease or increase the light localization and the light-matter interaction. Our methods offer flexible and efficient theoretical tools for the investigation of light-matter interaction, especially cavity quantum electrodynamics. Our findings significantly lower the requirements for optimization effort and fabrication precision and open up many promising practical possibilities.

Replacing the saddle-point approximation extensively adopted in previous literature, an exact expression for the Fourier transformation of electric field distributions of reflected and refracted polarised Gaussian beams is derived to investigate the spin Hall effect of light. A general method based upon the partial differential of the light intensity distributions of the reflected and refracted propagating beams is presented to determine the beam shifts from the spin Hall effect of light. Compared with the previous integration method along one direction reported in the literature, our method not only is much more explicit, but also enables us simultaneously to obtain the transverse and longitude shifts of the reflected and refracted wave packets. Furthermore, at any propagation distance away from the interface between two optical media, the shifts of the propagating beams and their split ones can be analytically expressed by means of transverse- and longitude-deflected angles.

Strongly coupled plasmonic nanostructures with sub-10 nm gaps can enable intense electric field enhancements which greatly benefit the various light-matter interactions. From the point view of practical applications, such nanostructures should be of low-cost, facile fabrication and processing, large-scale with high-yield of the ultrasmall gaps, and easy for integration with other functional components. However, nowadays techniques for reliable fabrication of these nanostructures usually involve complex, time-consuming, and expensive lithography procedures, which are limited either by their low-throughput or the small areas obtained. On the other hand, so far most of the studies on the sub-10 nm gap nanostructures mainly focused on the surface-enhanced Raman scattering and high-harmonic generations, while leaving other nonlinear optical properties unexplored. In this work, using a scalable process without any lithography procedures, we demonstrated a centimeter-scale ordered plasmonic nanorod array film (PNRAF) with well-defined sub-10 nm interparticle gaps as a versatile platform for strongly enhanced light-matter interactions. Specifically, we showed that due to its plasmon-induced localized electromagnetic field enhancements, the Au PNRAF could exhibit extraordinary intrinsic multi-photon avalanche luminescence (MAPL) and nonlinear saturable absorption (SA). Furthermore, the PNRAF can be easily integrated with semiconductor quantum dots (SQDs) as well as wide bandgap semiconductors to strongly enhance their fluorescence and photocurrent response, respectively. Our method can be easily generalized to nanorod array films consisting of other plasmonic metals and even semiconductor materials, which can have multiple functionalities derived from different materials. Overall, the findings in our study have offered a potential strategy for design and fabrication of nanostructures with ultrasmall gaps for future photonic and optoelectronic applications.

The non-interferometric phase retrieval technique based on the transport-of-intensity equation (TIE) is employed to calculate the missing phase information from the intensity measurement. However, since the limiting effect of the lens aperture is existed in the actual imaging system, a certain effect on the resolution of the recovery phase is under consideration. A phase retrieval technology based on multi-angle tilt light modulation is proposed. Firstly, a spatial light modulator (SLM) is introduced in the original lens-based intensity acquisition system. Then the modulation function is displayed on the SLM to make the parallel illumination into tilted illumination with various incident angles. Lastly, the recorded intensity images are synthesized to compute the phase information. The experimental results show that the proposed method can improve the resolution of recovery phase without compromising the numerical error of the recovery results.

Reaching the quantum optics limit of strong light-matter interactions between a single exciton and a plasmon mode is highly desirable, because it opens up possibilities to explore room-temperature quantum devices operating at the single-photon level. However, two challenges severely hinder the realization of this limit: the integration of single-exciton emitters with plasmonic nanostructures and making the coupling strength at the single-exciton level overcome the large damping of the plasmon mode. Here, we demonstrate that these two hindrances can be overcome by attaching individual $J$ aggregates to single cuboid Au@Ag nanorods. In such hybrid nanosystems, both the ultrasmall mode volume of $\ensuremath{\sim}71\text{ }\text{ }{\mathrm{nm}}^{3}$ and the ultrashort interaction distance of less than 0.9 nm make the coupling coefficient between a single $J$-aggregate exciton and the cuboid nanorod as high as $\ensuremath{\sim}41.6\text{ }\text{ }\mathrm{meV}$, enabling strong light-matter interactions to be achieved at the quantum optics limit in single open plasmonic nanocavities.

In this paper, we investigate second harmonic generation in a single hexagonal GaAs nanowire. An excellent frequency converter based on this nanowire excited using a femtosecond laser is demonstrated to operate over a range from 730 nm to 1960 nm, which is wider than previously reported ranges for nanowires in the literature. The converter always operates with a high conversion efficiency of ~10−5 W−1 which is ~103 times higher than that obtained from the surface of bulk GaAs. This nanoscale nolinear optical converter that simultaneously owns high efficiency and broad bandwidth may open a new way for application in imaging, bio-sensing and on-chip all-optical signal processing operations.

Centrosomal proteins have been implicated in the progression of human diseases. CEP131 plays important roles in centrosome duplication and genome stability, but its role in cancers remains largely unknown. Here, we showed that CEP131 expression was increased in hepatocellular carcinoma (HCC), compared to the paracarcinoma tissues, at both mRNA and protein levels. High CEP131 expression was closely associated with tumor size (P=0.020), tumor capsule (P=0.043), TNM stage (P=0.007) and tumor differentiation (P=0.019). Furthermore, patients with high expression of CEP131 were accompanied with worse overall and disease-free survivals in our and TCGA cohorts consisting of a total of 802 cases. The prognostic value of CEP131 was further confirmed by stratified survival analysis. Multivariate cox regression model indicated that CEP131 was an independent factor for overall survival (hazard ratio=1.762, 95% confident interval: 1.443-2.151, P

We report optical positioning of single quantum dots (QDs) in planar distributed Bragg reflector (DBR) cavity with an average position uncertainty of ≈20 nm using an optimized photoluminescence imaging method. We create single-photon sources based on these QDs in determined micropillar cavities. The brightness of the QD fluorescence is greatly enhanced on resonance with the fundamental mode of the cavity, leading to an high extraction efficiency of 68% ± 6% into a lens with numerical aperture of 0.65, and simultaneously exhibiting low multi-photon probability (g(2)(0) = 0.144 ± 0.012) at this collection efficiency.

We propose and experimentally demonstrate a series of $L_{n}$ slot photonic crystal (PhC) microcavities, which operate as refractive index (RI) gas sensors. The cavities are simply composed of a silicon slab triangular photonic crystal with $n$ holes replaced by a slot, which do not require sophisticated design or high fabrication resolution. With the increase in $n$ , the quality factor of the cavity exponentially increases, which is explained by the envelope of electric field approaching a Gaussian profile. An $L_{9}$ slot PhC microcavity with a quality factor exceeding 30 000, sensitivity of 421 nm per RI unit (RIU), and detection limit down to $1\times 10^{-5}$ RIU was experimentally demonstrated. The performance of the device is comparable with other fine-tuned PhC microcavity structures. Due to its simple structure and high fabrication tolerance, it could have wide applications in optical sensors.

The different fracture characteristics of self-compacting rock-filled concrete with large-size natural and recycled aggregate are analyzed by three-point bending experiment. According to the analysis of the crack propagation process, the fracture mechanism differences of self-compacting rock-filled concrete with large-size natural and recycled aggregate are discussed. The further analysis of the differences of fracture toughness, fracture energy, and are gain

Solid-state single-photon sources with high purity, high brightness and a large degree of linear polarization are appealing to photonic quantum technologies. However, high-performance single-photon sources based on InAs/GaAs quantum dots (QDs) so far are operating at near infrared range, which limits the detection efficiency and potential compatibility with atomic quantum memory in visible. Here, we explore GaAs droplet epitaxial QDs emitting in visible to achieve bright, pure and highly-polarized single-photon emission via coupling to photonic crystal cavities.