Manipulable and Hybridized,Ultralow‐Threshold Lasing in a Plasmonic Laser Using Elliptical InGaN/GaN Nanorods

Manipulating stimulated‐emission light in nanophotonic devices on scales smaller than their emission wavelengths to meet the requirements for optoelectronic integrations is a challenging but important step. Surface plasmon polaritons (SPPs) are one of the most promising candidates for sub‐wavelength optical confinement. In this study, based on the principle of surface plasmon amplification by the stimulated emission of radiation (SPASER), III‐Nitride‐based plasmonic nanolaser with hybrid metal–oxide–semiconductor (MOS) structures is designed. Using geometrically elliptical nanostructures fabricated by nanoimprint lithography, elliptical nanolasers able to demonstrate single‐mode and multimode lasing with an optical pumping power density as low as 0.3 kW cm^?2 at room temperature and a quality Q factor of up to 123 at a wavelength of ≈490 nm are achieved. The ultralow lasing threshold is attributed to the SPP‐coupling‐induced strong electric‐field‐confinement in the elliptical MOS structures. In accordance with the theoretical and experimental results, the size and shape of the nanorod are the keys for manipulating hybridization of the plasmonic and photonic lasing modes in the SPASER. This finding provides innovative insight that will contribute to realizing a new generation of optoelectronic and information devices.     

Low-threshold lasing in a plasmonic laser using nanoplate InGaN/GaN

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 en-hanced.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 charac-ters are mainly attributed to the strong confinement of electromagnetic wave in the low refractive index material,which im-prove the near field coupling between SPs and excitons.Such plasmonic laser should be useful in data storage applications,bio-logical application,light communication,especially for optoelectronic devices integrated into a system on a chip.     

Plasmonic‐Tuned Flash Cu Nanowelding with Ultrafast Photochemical‐Reducing and Interlocking on Flexible Plastics

Herein, a high‐performance copper nanowire (Cu NW) network (sheet resistance ≈ 17 Ω sq^?1, transmittance 88%) fabricated by plasmonic‐tuned flash welding (PFW) with ultrafast interlocking and photochemical reducing is reported, which greatly enhance the mechanical and chemical stability of Cu NWs. Xenon flash spectrum is tuned in an optimized distribution (maximized light intensity at 600 nm wavelength) through modulation of electron kinetic energy in the lamp by generating drift potential for preferential photothermal interactions. High‐intensity visible light is emitted by the plasmonic‐tuned flash, which strongly improves Cu nanowelding without oxidation. Near‐infrared spectrum of the flash induced an interlocking structure of NW/polyethylene terephthalate interface by exciting Cu NW surface plasmon polaritons (SPPs), increasing adhesion of the Cu nanonetwork by 208%. In addition, ultrafast photochemical reduction of Cu NWs is accomplished in air by flash‐induced electron excitations and relevant chemical reactions. The PFW effects of localized surface plasmons and SPPs on junction welding and adhesion strengthening of Cu network are theoretically studied as physical behaviors by finite‐difference time‐domain simulations. Finally, a transparent resistive memory and a touch screen panel are demonstrated by using the flash‐induced Cu NWs, showing versatile and practical uses of PFW‐treated Cu NW electrodes for transparent flexible electronics.     

A CdSe Nanowire/Quantum Dot Hybrid Architecture for Improving Solar Cell Performance

Incorporating colloidal CdSe quantum dots (QDs) into CdSe nanowire (NW)‐based photoelectrochemical solar cells increases their incident‐photon‐to‐carrier conversion efficiencies (IPCE) from 13% to 25% at 500 nm. While the effect could, in principle, stem from direct absorption and subsequent carrier generation by QDs, the overall IPCE increase occurs across the entire visible spectrum, even at wavelengths where the dots do not absorb light. This beneficial effect originates from an interplay between NWs and QDs where the latter fill voids between interconnected NWs, providing electrically accessible conduits, in turn, enabling better carrier transport to electrodes. The presence of QDs furthermore reduces the residual polarization anisotropy of random NW networks. Introducing QDs therefore addresses an important limiting constraint of NW photoelectrochemical solar cells. The effect appears to be general and may aid the future design and implementation of other NW‐based photovoltaics.     

Nickel Silicide Nanowire Arrays for Anti‐Reflective Electrodes in Photovoltaics

Conductive nanowires (NWs) provide several advantages as a template and electrode material for solar cells due to their favorable light scattering properties. While the majority of NW solar cell architectures studied are based on semiconductor materials, metallic NWs could provide equivalent anti‐reflection properties, while acting as a low‐resistance back contact for charge transport, and facilitate light scattering in thin layers of semiconductors coated on the surface. However, fabrication of single‐crystalline highly anti‐reflective NWs on low‐cost, flexible substrates remains a challenge to drive down the cost of NW solar cells. In this study, metallic Ni_xSi NW arrays are fabricated by a simple, bottom‐up, and low‐cost method based on the thermal decomposition of silane on the surface of flexible Ni foil substrates without the need for lithography, etching or catalysts. The optical properties of these NW arrays demonstrate broadband suppression of reflection to levels below 1% from 350 nm to 1100 nm, which is among the highest values reported for NWs. A simple route to control the diameter and density of the NWs is introduced based on variations in a carrier gas flow rate. A high‐resolution TEM, XRD and TEM‐EDS study of the NWs reveals that they are single crystalline, with the phase and composition varying between Ni₂Si and NiSi. The nanowire resistivity is measured to be 10^?4 Ω‐cm, suggesting their use as an efficient back electrode material for nanostructured solar cells with favorable light scattering properties.     

Plasmonically enhanced lasing by different size silver nanoparticles-silver film hybrid structure

We reported on the enhanced lasing in organic dyes based on plasmonic hybrid structure of Ag nanoparticles (NPs)-Ag film, the diameters of Ag NPs ranged from 20 nm to 100 nm. The lowest lasing threshold was achieved by the optimal size Ag NPs-Ag film hybrid structure, which was reduced by 5.2 times than that of the neat gain medium. Comparing to the separate Ag NPs or Ag film, the hybrid structure presented the more intense local electric field due to the plasmonics coupling between the localized surface plasmons of Ag NPs and the surface plasmon polariton of Ag film, and the stronger scattering due to the reinjection of the leaking photons by external feedback of Ag film. The effects of different sizes Ag NPs-Ag film hybrid structures on lasing were investigated. It found that when the Ag NPs in hybrid structure is small (diameter≤40 nm), the enhanced localized electric field plays a major role on enhanced lasing; with the increase of Ag NPs size, the enhanced electric field and scattering have comparable contribution on enhancing lasing; for the larger size Ag NPs-Ag film (diameter≥80 nm), the scattering effect is the dominant mechanism for random lasing. Then the lowest threshold was dominated by the balance of enhanced localized electric field and scattering effect. Our results could provide us a unique idea to effectively enhance the lasing of organic dyes, and realize the lower pumped threshold and stronger lasing.     

InAs/GaAs自组织量子点激发态的激射

将覆盖层引入生长停顿的量子点结构作为激光器有源区来研究量子点激光器受激发射机制 .由于强烈的能带填充效应 ,光致发光谱和电致发光谱中观察到对应于量子点激发态跃迁的谱峰 ,大激发时其强度超过基态跃迁对应的谱峰 .最后激发态跃迁达到阈值条件 ,激射能量比结构相似但不含量子点的激光器低 ,表明量子点激光器中首先实现受激发射是量子点的激发态     

Plasmonic Nanoneedle Arrays with Enhanced Hot Electron Photodetection for Near-IR Imaging

Hot electron photodetection based on metallic nanostructures is attracting significant attention due to its potential to overcome the limitation of the traditional semiconductor bandgap. To enable efficient hot electron photodetection for practical applications, it is necessary to achieve broadband and perfect light absorption within extremely thin plasmonic nanostructures using cost-effective fabrication techniques. In this study, an ultrahigh optical absorption (up to 97.3% in average across the spectral range of 1200−2400 nm) is demonstrated in the ultrathin plasmonic nanoneedle arrays (NNs) with thickness of 10 nm, based on an all-wet metal-assisted chemical etching process. The efficient hot electron generation, transport, and injection at the nanoscale apex of the nanoneedles facilitate the photodetector to achieve a record low noise equivalent power (NEP) of 4.4 × 10⁻¹² W Hz^−0.5 at the wavelength of 1300 nm. The hot-electron generation and injection process are elucidated through a transport model based on a Monte Carlo approach, which quantitatively matches the experimental data. The photodetector is further integrated into a light imaging system, as a demonstration of the exceptional imaging capabilities at the near-IR regime. The study presents a lithography-free, scalable, and cost-effective approach to enhance hot electron photodetection, with promising prospects for future imaging systems.     

Plasmonic Nanowire‐Enhanced Upconversion Luminescence for Anticounterfeit Devices

A novel, efficient, cost‐effective, and high‐level security performance anticounterfeit device achieved by plasmonic‐enhanced upconversion luminescence (UCL) is demonstrated. The plasmonic architecture consists of the randomly dispersed Ag nanowires (AgNWs) network, upconversion nanoparticles (UCNPs) monolayer, and metal film, in which the UCL is enhanced by a few tens, compared to reference sample, becuase the plasmonic modes lead to the concentration of the incident near infrared (NIR) light in the UCNPs monolayer. In the configuration, both the localized surface plasmons (LSPs) around the metallic nanostructures and gap plasmon polaritons (GPPs) confined in the UCNPs monolayer, significantly contribute to the UCL enhancement. The UCL enhancement mechanism resulting from enhanced NIR absorption, boosted internal quantum process, and formation of strong plasmonic hot spots in the plasmonic architecture is analyzed theoretically and numerically. More interestingly, a proof‐of‐concept anticounterfeit device using the plasmonic‐enhanced UCL is proposed, through which a nonreusable and high‐level cost‐effective security device protecting the genuine products is realized.     

Anticompetition Between Laser Modes in Quantum-Dot Laser

Anticompetition behavior is observed in a InAs quantum-dot (QD) laser with external wavelength control. Unlike the competition behavior observed in other QD lasers, in this experiment, the laser emission induced by external feedback at the ground state wavelength improves the excited-state emission at 1170 nm by 13 dB. Such an anticompetition phenomenon is most obvious as the feedback wavelength differs from 1250 nm, the original lasing wavelength, by 15 nm. This anticompetition behavior is explained by the sharing of QDs between the laser emission induced by the feedback and the original laser oscillation     

Plasmon‐Enhanced Blue Upconversion Luminescence by Indium Nanocrystals

Numerous endeavors have been undertaken to gain enhanced upconversion luminescence via surface plasmon resonance (SPR) generated by specially designed nanostructures of noble metals (e.g., Au, Ag). However, the SPR response of these metals is usually weak in the ultraviolet (UV) region because of their intrinsic electronic configurations; thus, only green and red upconversion emissions can undergo significant plasmonic enhancement yet without selectivity, while an efficient approach to selectively enhancing the blue upconversion luminescence has been lacking. Herein, by integrating the pronounced UV SPR of silica‐coated indium nanocrystals (InNCs) with blue‐emission upconversion nanoparticles (UCNPs) of NaYbF₄:Tm, an up to tenfold selective luminescence enhancement at 450 nm is obtained upon 980 nm laser excitation. Precise manipulation of the silica shell thickness suggests an optimal working distance of 3 nm between InNCs and UCNPs. This study has, for the first time, realized selective blue upconversion luminescence enhancement by using an inexpensive, non‐noble metal material, which will not only enrich the fundamental investigations of SPR‐enhanced upconversion emission, but also widen the applications of blue light‐emitting nanomaterials, for example, in therapeutics.     

InAs/GaAs自组织量子点激发态的激射

将覆盖层引入生长停顿的量子点结构作为激光器有源区来研究量子点激光器受激发射机制．由于强烈的能带填充效应, 光致发光谱和电致发光谱中观察到对应于量子点激发态跃迁的谱峰,大激发时其强度超过基态跃迁对应的谱峰．最后激发态跃迁达到阈值条件, 激射能量比结构相似但不含量子点的激光器低,表明量子点激光器中首先实现受激发射是量子点的激发态．     

Remote Biosensing with Polychromatic Optical Waveguide Using Blue Light‐Emitting Organic Nanowires Hybridized with Quantum Dots

Nanometer‐scale optical waveguides are attractive due to their potential applicability in photonic integration, optoelectronic communication, and optical sensors. Nanoscale white light‐emitting and/or polychromatic optical waveguides are desired for miniature white‐light generators in microphotonic circuits. Here, polychromatic (i.e., blue, green, and red) optical waveguiding characteristics are presented using a novel hybrid composite of highly crystalline blue light‐emitting organic nanowires (NWs) combined with blue, green, and red CdSe/ZnS quantum dots (QDs). Near white‐color waveguiding is achieved for organic NWs hybridized with green and red QDs. Light, emitted from QDs, can be transferred to the organic NW and then optically waveguided through highly packed π‐conjugated organic molecules in the NW with different decay characteristics. Remote biosensing using dye‐attached biomaterials is presented by adapting the transportation of QD‐emitted light through the organic NW.     

Flexible Broadband Image Sensors with SnS Quantum Dots/Zn2SnO4 Nanowires Hybrid Nanostructures

Broadband image sensors are widely studied and applied in many fields. However, developing high‐performance flexible broadband imaging is still a great challenge that needs to be overcome. This study demonstrates a flexible broadband image sensor with SnS quantum dots (QDs)/Zn₂SnO₄ (ZTO) nanowires (NWs) hybrid nanostructures as the sensing elements, which is prepared by decorating ZTO NWs with SnS QDs via a two‐step vapor deposition method. Compared with pristine ZTO NWs, the hybrid QDs/NWs exhibit much higher photoconductive gain and specific detectivity in UV region and extended photoresponse ranging from UV to NIR region. In addition, individual hybrid QDs/NW photodetector built on polyethylene terephthalate substrate shows an excellent flexibility, mechanical stability, folding endurance, and long‐term stability. Integrated into a 10 × 10 array, a flexible broadband image sensor is fabricated. Under bending states, the flexible image sensor can still identify clearly the target images composed of white light and red light, revealing the outstanding target identification ability. The superior performance of the devices indicates that the QDs/NWs hybrid nanostructures have a tremendous application potential in future flexible broadband imaging technology.     

表面等离子阵列结构中的耦合增强反射效应其红外光谱增强特性研究

使用聚焦离子束刻蚀的方法制备了不同间距的表面等离子结构阵列,研究了由方形和圆形所构成的阵列在不同间距下的光学反应.实验表明,粒子之间耦合效应随着间距的显著减小而逐渐变强,从弱耦合变化为强耦合状态.当间距小于30 nm时,发现耦合增强的反射效应,共振波长也会随着间距的减小而发生红移.将制备的超小间距纳米阵列和傅里叶变换光谱仪的ATR附件相耦合,实验验证了相关阵列结构在红外光谱增强方面的显著效果.相关的发现和表面等离子阵列结构可以在传感、探测和光谱增强等方面取得一定的应用.     

Tuning the spectrometric properties of white light by surface plasmon effect using Ag nanoparticles in a colour converting light-emitting diode

We report on the spectral tunability of white light by localized surface plasmon (LSP) effect in a colour converting hybrid device made of CdSe/ZnS quantum dots (QDs) integrated on InGaN/GaN blue light-emitting diodes (LEDs). Silver (Ag) nanoparticles (NPs) are mixed with QDs for generating LSP effect. When the plasmon absorption of Ag NPs is synchronized to the QW emission at 448 nm, the NPs selectively absorb the blue light and subsequently enhance the QD emission. Using this energy transfer scheme, the (x, y) chromaticity coordinates of the hybrid white LED was tuned from (0.32, 0.17) to (0.43, 0.26), and thereby generated warm white light emission with correlated colour temperature (CCT) around 1800 K. Moreover, a 47% enhancement in the external quantum efficiency (EQE) was realized.     

Highly Efficient and Bendable Organic Solar Cells with Solution‐Processed Silver Nanowire Electrodes

Highly efficient and bendable organic solar cells (OSCs) are fabricated using solution‐processed silver nanowire (Ag NW) electrodes. The Ag NW films were highly transparent (diffusive transmittance ≈ 95% at a wavelength of 550 nm), highly conductive (sheet resistance ≈ 10 Ω sq^?1), and highly flexible (change in resistance ≈ 1.1 ± 1% at a bending radius of ≈200 μm). Power conversion efficiencies of ≈5.80 and 5.02% were obtained for devices fabricated on Ag NWs/glass and Ag NWs/poly(ethylene terephthalate) (PET), respectively. Moreover, the bendable devices fabricated using the Ag NWs/PET films decrease slightly in their efficiency (to ≈96% of the initial value) even after the devices had been bent 1000 times with a radius of ≈1.5 mm.     

Ag纳米颗粒有机薄膜受激辐射增强研究

为进一步降低有机半导体材料的激射阈值,文章研究利用银纳米颗粒的表面等离子体共振效应来实现对有机半导体薄膜受激辐射的增强.将制备好的Ag纳米溶液旋涂于玻璃基底上,然后在其上再旋涂PS:Alq3:DCJTB有机薄膜发光层,构成平面波导结构.用355nm波长的YAG激光泵浦样品.实验发现:相比于无Ag纳米颗粒情况,有Ag纳米...     

All-In-One Detection,Removal and Recovery of Hg2+ in Industrial Wastewater with Plasmonic Schottky Heterostructures

The effective governance of Hg²⁺ in environmental wastewater is of profound significance to deal with the global pollution issues. However, the present methodologies usually only focused on a single function of either detection or removal, which encounters severe secondary pollution and cumbersome operation cost, while the integration of Hg²⁺ detection, removal, and recovery in one process is barely realized. In this study, an All-In-One photoelectrochemical system is built combining the detection, removal, and recovery of Hg²⁺ pollutant in a single process, by ingeniously developing a fundamental principle, namely alloying-induced plasmonic quenching mechanism in Schottky heterostructures. Briefly, the high-efficiency removal and recovery of Hg²⁺ in wastewater is realized via the favorable alloying of Hg in Ag nanoparticles that well-dispersed on the free-standing WO₃ nanoplate networks. The formation of Ag–Hg alloy future leads to a remarkable plasmonic quenching effect of the Ag nanoparticles, which is used to modulate the photoelectrochemical singles to realize the high-precision detection. Through this ingenious design, an ultralow Hg²⁺ detection limit of 0.296 nm is achieved with a broad detection range up to 12.5 µm , and meanwhile realize a removal/recovery rate of 100% in single Hg²⁺ solution and 97 ± 2% in industrial wastewater with multiple contamination ions. The detection and removal/recovery performance parameters reported in the study are much better as compared to the recently reported single function detection or removal/recovery systems. This work opens a fresh avenue in tackling the problem of heavy metal pollution using plasmonic Schottky heterostructure based All-In-One systems.     

Engineering Symmetry‐Breaking Nanocrescent Arrays for Nanolasing

This paper describes a symmetry‐breaking plasmonic lattice structure that can support narrow resonances as optical feedback for nanolasing. A scalable technique is developed to fabricate nanocrescent arrays with low‐structural symmetry unit cells to achieve in‐plane quadrupolar lattice plasmon modes. These lattice plasmons with extremely narrow linewidths preserve nonzero net dipole moments under normal excitation. Ultrafast band‐edge lasing can be switched on and off by changing the polarization of the incident pump light. The quadrupolar lattice plasmon lasing process is simulated with a semi‐quantum model and the sharp tips on the nanocrescents accelerate the lasing buildup process and enhance stimulated emission.