- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2019
- Mach Zehnder Interferometer
- Convolution code
- Lithium Niobate
- Parity
- Electro-optic
- Optoelectronic Information Science and Engineering
- DIT University
-
Enhancement of the second harmonic signal of nonlinear crystals by self-assembled gold nanoparticles
摘要： In second harmonic generation (SHG), the energy of two incoming photons, e.g., from a femtosecond laser, can be combined in one outgoing photon of twice the energy, e.g., by means of a nonlinear crystal. The SHG efficiency, however, is limited. In this work, the harvested signal is maximized by composing a hybrid system consisting of a nonlinear crystal with a dense coverage of plasmonic nanostructures separated by narrow gaps. The method of self-assembled diblock-copolymer-based micellar lithography with subsequent electroless deposition is employed to cover the whole surface of a lithium niobate (LiNbO3) crystal. The interaction of plasmonic nanostructures with light leads to a strong electric near-field in the adjacent crystal. This near-field is harnessed to enhance the near-surface SHG signal from the nonlinear crystal. At the plasmon resonance of the gold nanoparticles, a pronounced enhancement of about 60-fold SHG is observed compared to the bare crystal within the confocal volume of a laser spot.
关键词： gold nanoparticles,nonlinear crystal,second harmonic generation,lithium niobate,plasmonic nanostructures,electroless deposition,self-assembled diblock-copolymer-based micellar lithography,LiNbO3,SHG
更新于2025-09-23 15:19:57
-
In situ forming of ternary metal fluoride thin films with excellent Li storage performance by pulsed laser deposition
摘要： In the field of lithium ion battery, conversion-based metal fluoride cathodes are attractive for their excellent theoretical capacity and high voltage. However, the utilization of binary metal fluorides is severely hindered by irreversibility and large voltage hysteresis. The introduction of ternary metal fluorides, like AgCuF3 and CuxFe1-xF2, brings hope to address these shortcomings. To better understand the basic mechanism of conversion reaction in ternary metal fluoride cathodes, the Cu–Fe–F (CFF) thin films were successfully grown in situ by pulsed laser deposition in this work. The physico-chemical properties and electrochemical performance were discussed. Such a CFF solid solution phase presented great cycle stability (82% capacity remains after 100 cycles at current density of 285 mA g?1) and higher energy efficiency (71.8%), which can be attributed to the reversible structural rearrangement after the delithiation process disclosed by ex situ XPS, high-resolution TEM, and selected-area electron diffraction.
关键词： Thin film,Ternary metal fluoride,Lithium ion battery,Pulsed laser deposition
更新于2025-09-23 15:19:57
-
Piezoelectric Transduction of a Wavelength-Scale Mechanical Waveguide
摘要： We present a piezoelectric transducer in thin-film lithium niobate that converts a 1.7-GHz microwave signal to a mechanical wave in a single mode of a 1-μm-wide waveguide. We measure a ?12-dB conversion efficiency that is limited by material loss. The design method we employ is widely applicable to transduction in wavelength-scale structures in emerging phononic circuits such as those needed for efficient piezo-optomechanical converters and spin-phonon transducers.
关键词： phononic circuits,lithium niobate,piezoelectric transduction,piezo-optomechanical converters,mechanical waveguide,spin-phonon transducers
更新于2025-09-23 15:19:57
-
Optimization of laser-target parameters for the production of stable lithium beam
摘要： A laser ion source coupled with a radio frequency quadrupole linac accelerator is being proposed as a suitable system for the production of a low energy, high-current stable lithium beam. In order to maximize the lithium yield, plasmas generated by laser ablation of different materials based on lithium (Li, LiOH, and LiNbO3) have been characterized by using a Faraday cup and an electrostatic ion analyzer in the time of flight configuration. A wide range of laser power density has been investigated (109–1012 W/cm2) using two Nd:YAG lasers operating at different wavelengths (1064 nm and 532 nm), pulse durations (6 ns and 17 ns), and maximum energies (1400 mJ and 210 mJ). This paper outlines the pros and cons of the investigated materials by studying how the ion energy, yields, and charge state distributions are modified when the laser power density is changed. Considerable attention has been paid to the higher charge states of oxygen, which may occur with the same mass-to-charge ratio of Li3+. The analysis has evidenced that LiNbO3 represents a valid target since it allows minimizing the O6+/7Li3+ ratio down to 2.5% by using a laser power density of 1.8 × 1010 W/cm2. For such a condition, a Li3+ current of 1.4 mA/cm2 has been measured.
关键词： oxygen contamination,laser ion source,lithium beam,charge state distributions,laser ablation
更新于2025-09-23 15:19:57
-
Self-assembled shape evolution of the domain wall and formation of nanodomain wall traces induced by multiple IR laser pulse irradiation in lithium niobate
摘要： The formation of the domain structure in congruent lithium niobate crystals by multiple pulse irradiation using an infrared laser was studied experimentally. The qualitative change of the domain wall shape with an increase of the pulse number was revealed. The chains of isolated nanodomains representing the domain wall traces appeared after each laser pulse irradiation in the samples with an irradiated polar surface covered by an indium–tin oxide layer. This effect allowed extraction of the detailed information about the evolution of the domain wall shape. The domain kinetics under the action of the pyroelectric field has been considered. The mechanism of the self-assembled shape evolution of the moving domain wall as a result of the local wall accelerations and retardations caused by the shape fluctuations (bumps and valleys) was proposed. The experimentally observed formation of the quasi-regular comb-like domain structures with randomly distributed bumps and valleys was confirmed by computer simulation. The discovered effects allowed us to create the stable random and quasi-regular domain structures and open the way for further development of the domain engineering methods.
关键词： pyroelectric field,infrared laser,nanodomains,domain wall shape evolution,lithium niobate,domain structure
更新于2025-09-23 15:19:57
-
ANALYSIS OF THE PROPERTIES OF AW2099 ALUMINIUM-LITHIUM ALLOY WELDED BY LASER BEAM WITH AW5087 ALUMINIUM-MAGNESIUM FILLER MATERIAL
摘要： EN AW2099 aluminium lithium alloy, 2.0 mm in thickness, was used as an experimental material. EN AW2099 belongs to the 3rd generation of aluminium lithium alloys. The third generation was developed to improve the disadvantages of the previous generation, such as anisotropy in mechanical properties, low fracture toughness, corrosion resistance and resistance to fatigue crack growth, as well. Aluminium magnesium 5087 ?ller wire with a diameter of 1.2 mm was used for the welding. Crack free weld joints were produced after an optimization of welding parameters. The microstructure of weld metal and mechanical properties of weld joints were investigated. Equiaxed zone (EQZ) was observed at the fusion boundary. The character of grains changed in the direction towards the weld centre, from the columnar dendrite zone to equiaxed dendrite zone in the weld centre. The microstructure of the weld metal matrix consisted of α-aluminium. Alloying elements enrichment was found at the inter-dendritic areas, namely copper and magnesium. The microhardness decrease in the weld metal due to a dissolution of strengthening precipitates was measured. The microhardness was slightly higher in comparison to a weld produced by a laser welding without a ?ller material. The tensile strength of the weld joint reached around 67 % of the base material’s strength and the fracture occurred in the weld metal.
关键词： electron microscopy,microstructure,Aluminium lithium alloy,laser beam welding,equiaxed zone,mechanical properties
更新于2025-09-23 15:19:57
-
High Quality Entangled Photon Pair Generation in Periodically Poled Thin-Film Lithium Niobate Waveguides
摘要： A thin-film periodically poled lithium niobate waveguide was designed and fabricated which generates entangled photon pairs at telecommunications wavelengths with high coincidences-to-accidentals counts ratio CAR > 67000, two-photon interference visibility V > 99%, and heralded single-photon autocorrelation g(0) < 0.025. Nondestructive in situ diagnostics were used to determine the poling quality in 3D. Megahertz rates of photon pairs were generated by less than a milliwatt of pump power, simplifying the pump requirements and dissipation compared to traditional spontaneous parametric down-conversion lithium niobate devices.
关键词： lithium niobate waveguides,quantum information processing,entangled photon pairs,telecommunications wavelengths
更新于2025-09-23 15:19:57
-
Laser Micromachining of Lithium Niobate-Based Resonant Sensors towards Medical Devices Applications
摘要： This paper presents a micromachining process for lithium niobate (LiNbO3) material for the rapid prototyping of a resonant sensor design for medical devices applications. Laser micromachining was used to fabricate samples of lithium niobate material. A qualitative visual check of the surface was performed using scanning electron microscopy. The surface roughness was quantitatively investigated using an optical surface profiler. A surface roughness of 0.526 μm was achieved by laser micromachining. The performance of the laser-micromachined sensor has been examined in different working environments and different modes of operation. The sensor exhibits a Quality-factor (Q-factor) of 646 in a vacuum; and a Q-factor of 222 in air. The good match between the modelling and experimental results shows that the laser-micromachined sensor has a high potential to be used as a resonance biosensor.
关键词： medical devices,laser micromachining,sensors,lithium niobate,biosensors
更新于2025-09-23 15:19:57
-
Solution-processed blue quantum-dot light-emitting diodes based on double hole transport layers: Charge injection balance, solvent erosion control and performance improvement
摘要： Solution processed quantum-dot based light emitting diodes (QLEDs) usually suffer from the issues of imbalanced carrier injection (especially for blue QLEDs) and solvent erosion, which prevents these devices from reaching high performance. Here we report a simple and effective method of promoting hole injection and mitigating solvent erosion simultaneously for fabricating high-performance blue QLEDs. Poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))-diphenylamine)] (TFB)/Lithium bis(trifluoromethanesulfonimide) (Li-TFSI)-doped poly(9-vinlycarbazole) (PVK) bi-layers with smooth surfaces/interfaces, prepared via a solution-process by utilizing 1,4-dioxane as the solvent for PVK, were used as hole transport layers (HTLs) for improving the performance of blue QLEDs. The TFB/Li-doped PVK based QLED records 5829 cd/m2 of maximum brightness and 5.37% of peak EQE, which represents 1.1-fold increase in brightness and ~11.5-fold increase in EQE as compared with the devices based on TFB-only HTLs. The enhanced performance for these TFB/Li-doped PVK based QLEDs can be ascribed to more efficient hole injection offered by Li-doped bilayer HTLs with smooth surfaces/interfaces and stepwise energy level alignment. The CIE 1931 color coordinates (0.15, 0.03) for these TFB/Li-doped PVK based QLEDs are close to the National Television System Committee (NTSC) standard blue CIE coordinates, showing promise for use in next-generation full-color displays. This work provides a facile solution method of fabricating TFB/Li-doped PVK bi-layers with smooth surfaces/interfaces and proves the superiority of these TFB/Li-doped PVK bi-layered HTLs in hole transport and injection for high-performance blue QLEDs.
关键词： double hole transport layers,blue quantum-dot light-emitting diodes,charge injection；Lithium salt doped hole transport layer,solvent erosion,solution processability
更新于2025-09-23 15:19:57
-
Controlled Engineering Nano-sized FeOOH@ZnO Hetero-Structures on Reduced Graphene Oxide for Lithium ion Storage and Photo-Fenton Reaction
摘要： In this work, a nano-sized goethite and zinc oxide hetero-structure (FeOOH@ZnO) dispersed on reduced graphene oxide (RGO) sheets to construct a ternary composite (FeOOH@ZnO/RGO) is first synthesized by a stepped graphene oxide (GO) deoxygenation process. Ferrous ion (Fe2+) and metal Zn were employed as reducing agents, which were transformed to corresponding FeOOH and ZnO nanoparticles to form a hetero-structure in the reaction. Particularly, the size of the nanoparticles can be controlled by limiting the growth kinetics in this work. As a result, porous RGO architecture is constructed with well-dispersed hetero-structured nanoparticles constituted by FeOOH and ZnO nano-crystals encapsulated. The FeOOH@ZnO/RGO composite exhibits unique lithium ion storage properties as anode for lithium ion batteries. And compared with the binary FeOOH/RGO and ZnO/RGO composites, the ternary FeOOH@ZnO/RGO composite shows the best battery performance as anode for lithium ion batteries and the best photo-Fenton degradation activity toward methylene blue (MB) degradation under simulated sunlight irradiation. The preparation route for FeOOH@ZnO/RGO composite is straightforward, effective and has great potential to be scaled-up.
关键词： zinc oxide,goethite,graphene,methylene blue degradation,photo-Fenton,lithium ion batteries
更新于2025-09-23 15:19:57