Fabrication of Two-Dimensional Photonic Crystals with Controlled Defects by Combination of Holographic Lithography and Two-Photon Polymerization

一个新第三的相片聚合物系统在由单个光子、二光子的相片聚合的联合与控制缺点制作 photonic 晶体(PhCs ) 被使用。以前的过程能在一步舞记录与生产 PhCs 一低力量(十 mW ) 在 532 nm 的连续波浪的激光，当后者能创造需要的缺点时。材料，光安装和初步的试验性的结果的准备被给。与另外的方法相比，这条途径为可见的光的使用更可存取、方便并且有快速并且经济地在大规模做 PhCs 并且确切介绍任何缺点的优点，特别为三维的结构。

Effect of Solvents on the Absorption Properties of GaP Nanocrystals

GaP nanocrystals were synthesized by both the organic solvent reflux and high temperature high pressure benzene thermal synthesis methods.The effect of organic solvent on the optical absorption properties of GaP nanocrystals were studied.The results show that crystal grains of the sample synthesized by the latter method have better quality and uniformity.The solvents which consist of polar molecules and form strong chemical bonds with Ga atoms cause obvious redshift of the absorption spectra of GaP nanocrystals.The absorption spectra redshift much more if the solvent molecules have π electrons which involved in the formation of complex bond between Ga atoms and solvent molecules.

LOW TEMPERATURE PROPERTIES OF Tb-DOPED Sr_(1-x)Ba_(x)Nb_(2)O_(6)(SBN)CRYSTALS

Tb-doped SBN crystals were prepared by the Czochralski technique.Their dielectric,ferroelectric,and pyroelectric properties were studied.A low temperature phase transition between two polar phases was revealed by the anomalies of the dielectric and pyroelectric properties;the polar axis changes its direction during this transition.The point group of the low temperature phase may be mm2,m or 1.

Growth,Defects and Non-critical Phase Matching of Nb Doped KTP Crystals

A series of Nb doped KTP crystals are grown with seed Aux method and Hux pulling method.The results of our investigation on growth,morphology defects of the crystals are reported in this paper.We obtained the relationship between Nb contents and second-harmonic generation angles of the crystals.Noncritical phase matching has been realized by 4%Nb doped KTP crystal for Nd:YAG laser 1.06μm output.

Sduties on Modification of Pb_(1-x)BaxNb_(2)O_(6) Crystals

This paper reports the growth of pqre and Na,K modified lead barium niobate crystals and the measurement of their dielectric and structure properties.Exprimental results show that both pure and Na,K modified lead barium niobate crystals have growth striations.All the crystals belong to 4mm point group of tetragonal system at room temperature.Their Curie temperature are 379℃,389℃ and 473℃,respectively.

Formation of the Bicrystal Structure of KTiOPO_(4) Crystals

In this paper,by comparing the three possible combinations of the basic structure unit TiO_(6) octahedra,a simple model is proposed to explain the cause of the formation of the bicrystal structure in KTiOPO_(4)(KTP)crystals.The theoretical morphology of KTP crystal is studied and the rate of the appearance possibilities of different faces are obtained.The relationships between bicrystal structure and crystal properties are discussed.

Light-induced acoustic effect in LiNbO3：Fe：Ce crystals

The phenomena of acoustic emission in LiNbO3：Fe：Ce crystals have been observed in the process of light-induced quasi-breakdown. It is found that the ultra-high frequency acoustic signal introduced into the crystal is modulated by the low frequency acoustic waves. Its frequency increases with the increase of the intensity of incident light and its jump period of breakdown is the same as that of the photovoltaic current Ic, the change of light-induced refractive index △n and the diffracted light intensity L. This phenomenon has been analysed in this paper, which is caused by the inverse piezoelectric strain effect of the jump of space charge field during the quasi-breakdown.

Cu-Doped KNSBN Single Crystals

The preparation procedure, the transmissivity, and the two-wave coupling properties of coppermodified potassium sodium strontium barium niobate (KNSBN) crystals are reported. The Cu ions doped in KNSBN can form two deep energy levels. This means that they are able to act as centers for free charge carrier stimulation and recombination. The two-wave coupling gain coefficient of KNSBN: Cu is two times larger than that of KNSBN. The photorefractive sensitivity of KNSBN: Cu is estimated to be in the order of 10^(-3)cm^(2)/J.

A Study of 90°Ferroelectric Domains in Potassium Tantalate Niobate Crystals by Means of Transmission Electron Microscopy

By flux method,potassium tantalate niobate crystals with 46%Nb contents were prepared.In this material 90°a-type domains with(011)and(01ī)walls were observed by a transmission electron microscope,and the nature of fringe patterns associated with these domain walls was analysed.According to the extinction rules for the domain walls,the displacement vector R along<01ī>direction can be determined.Finally,using a selected area electron diffraction method,we examined the crystallographic character of these 90°domains and defined the ratio of lattice parameters c to a.

Diffraction from the Second-Order Photorefractive Grating in Paraelectric KTa_(1-x)Nb_(x)O_(3) Crystals

Diffraction from the second-order photorefractive grating written in KTa_(1-x)Nb_(x)O_(3)(x=0.32)crystal with cubic phase has been observed for the first time.The behaviors of this diffraction have been investigated experimentally.Some qualitative explanations have been proposed.

Rapid epitaxy of 2-inch and high-quality α-Ga_(2)O_(3) films by mist-CVD method

High thickness uniformity and large-scale films of α-Ga_(2)O_(3) are crucial factors for the development of power devices.In this work, a high-quality 2-inch α-Ga_(2)O_(3) epitaxial film on c-plane sapphire substrates was prepared by the mist-CVD method.The growth rate and phase control mechanisms were systematically investigated. The growth rate of the α-Ga_(2)O_(3) films was limited by the evaporation of the microdroplets containing gallium acetylacetonate. By adjusting the substrate position(z) from 80 to 50 mm, the growth rate was increased from 307 nm/h to 1.45 μm/h when the growth temperature was fixed at 520 °C.When the growth temperature exceeded 560 °C, ε-Ga_(2)O_(3) was observed to form at the edges of 2-inch sapphire substrate.Phase control was achieved by adjusting the growth temperature. When the growth temperature was 540 °C and the substrate position was 50 mm, the full-width at half maximum(FWHM) of the rocking curves for the(0006) and(10-14) planes were 0.023° and 1.17°. The screw and edge dislocations were 2.3 × 10~6 and 3.9 × 10~(10)cm~(-2), respectively. Furthermore, the bandgaps and optical transmittance of α-Ga_(2)O_(3) films grown under different conditions were characterized utilizing UV-visible and near-IR scanning spectra.

Potassium tantalate niobate crystals:Efficient quadratic electro-optic materials and their laser modulation technology

Electro-optic(EO)crystals are important material for all-solid-state laser technology,which can be used to fabricate various laser modulators,such as EO switches,laser deflectors,and optical waveguide.The improvements in new high-efficiency EO crystal materials have held great significance to the development of laser technology.Potassium tantalate niobate(KTN)is a popular multifunctional crystal because of its remarkable and excellent quadratic EO effect.KTN EO modulation technology offers numerous advantages,such as high efficiency,good stability,a quick response time,and inertia-free characteristics.In this paper,we summarize the research progress of KTN series crystals systemically,including the theoretical exploration on quadratic EO effect,solid-melt crystal growth technique,comprehensive physical characterization,new physical effect and mechanisms exploration,new EO devices development and design.The EO modulation technique based on the Kerr effect of KTN series crystal offers obvious advantages in reducing the drive voltage and device size,which could better meet the developmental needs of future lasers with a wide wavelength,miniaturization,and integration.This may provide theoretical guidance and an experimental basis for the design and development of new EO crystal devices and promote the development of laser technology.

Prediction of one-dimensional CrN nanostructure as a promising ferromagnetic half-metal

Searching for one-dimensional(1D)nanostructure with ferromagnetic(FM)half-metallicity is of significance for the development of miniature spintronic devices.Here,based on the first-principles calculations,we propose that the 1D CrN nanostructure is a FM half-metal,which can generate the fully spin-polarized current.The ab initio molecular dynamic simulation and the phonon spectrum calculation demonstrate that the 1D CrN nanostructure is thermodynamically stable.The partially occupied Cr-d orbitals endow the nanostructure with FM half-metallicity,in which the half-metallic gap(?s)reaches up to 1.58 eV.The ferromagnetism in the nanostructure is attributed to the superexchange interaction between the magnetic Cr atoms,and a sizable magnetocrystalline anisotropy energy(MAE)is obtained.Moreover,the transverse stretching of nanostructure can effectively modulate?s and MAE,accompanied by the preservation of half-metallicity.A nanocable is designed by encapsulating the CrN nanostructure with a BN nanotube,and the intriguing magnetic and electronic properties of the nanostructure are retained.These novel characteristics render the 1D CrN nanostructure as a compelling candidate for exploiting high-performance spintronic devices.

Resonant perfect absorption of molybdenum disulfide beyond the bandgap

Light absorption and radiation are fundamental processes in optical science and engineering.Materials with perfect absorption properties play an important role in numerous optical applications.Following the meteoric rise of MoS_(2)material,global opportunities and challenges coexist due to its extremely weak light-matter interaction capability beyond its energy band.In this work,we designed a kind of sandwich resonance structure and investigated MoS_(2)as a perfect absorber in the infrared spectrum that should be transparent according to the optical band theory.The infrared absorption properties of W or Au/MoS_(2)/Au models at 800 nm-2400 nm were systematic simulated.By optimizing the structural parameters,the resonant wavelength of perfect absorption can be modulated from 830 nm to 1700 nm with angle insensitivity and polar independence.Moreover,we discovered that the bandwidth of absorption exceeding 50%of the W-top model reaches500 nm,while that of the Au-top model is less than 100 nm,indicating that the top metal material has a great influence on the resonance absorption spectrum.Our work provides a practical route for enhancing and manipulating the light-matter interactions of low-dimensional materials beyond their own band gaps,which will be critical in the future design and implementation of optoelectronic devices and systems.

Diverse Structural Design Strategies of MXene‑Based Macrostructure for High‑Performance Electromagnetic Interference Shielding

There is an urgent demand for flexible,lightweight,mechanically robust,excellent electromagnetic interference(EMI)shielding materials.Two-dimensional(2D)transition metal carbides/nitrides(MXenes)have been potential candidates for the construction of excellent EMI shielding materials due to their great electrical electroconductibility,favorable mechanical nature such as flexibility,large aspect ratios,and simple processability in aqueous media.The applicability of MXenes for EMI shielding has been intensively explored;thus,reviewing the relevant research is beneficial for advancing the design of high-performance MXene-based EMI shields.Herein,recent progress in MXene-based macrostructure development is reviewed,including the associated EMI shielding mechanisms.In particular,various structural design strategies for MXene-based EMI shielding materials are highlighted and explored.In the end,the difficulties and views for the future growth of MXene-based EMI shields are proposed.This review aims to drive the growth of high-performance MXene-based EMI shielding macrostructures on basis of rational structural design and the future high-efficiency utilization of MXene.

Researches on the Growth Habit and Optical Properties of Fe^(3+) Ion Doped KDP Crystal

During the process of KDP crystal growth, metal ions strongly affect the growth habit and optical properties of KDP single crystal. In this paper, KDP crystals were grown from an aqueous solution doped with different concentration of Fe^3＋ dopant by traditional temperaturereduction method and ＂point-seed＂ rapid growth method. Furthermore, we examined the light scatter and measured the transmission of these KDP crystals. It is found that the dopant of Fe^3＋ ion can improve the stability of the KDP growth solution when its concentration is less than 30 ppm. The effects of Fe^3＋ ion on the growth habit and optical properties of KDP crystal are also obvious.

Shape control technology during electrochemical synthesis of gold nanoparticles

Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor （HAuC14） to an electrolyzed aqueous solution of poly（N-vinylpyrrolidone） （PVP） and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,＇ respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H＋ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.

Compact Diode-Pumped Continuous-Wave Nd：LuVO4 Lasers Operated at 916 nm and 458 nm

我们报导协议抽二极管连续波浪(CW ) Nd : LuVO4 激光第一次在 916nm 和 458 nm 操作了。在 916nm 激光的 780 mW 的最大的产量力量与 9.3% 的斜坡效率被获得。我们产生采用 atype 的 458 nm 蓝色激光的 50 m W -- 我批评匹配阶段的 LBO 水晶。

High-Efficiency Mid-Infrared Picosecond MgO:PPLN Single Resonant Optical Parametric Oscillator

We demonstrate a high-emciency mid-infrared picosecond optical parametric oscillator （OPO） based on MgO doped periodically poled lithium niobate （MgO：PPLN） with a laser diode array （LDA） pumped Innoslab amplifier as the pumping source. Under a 16 W synchronously pumping power, 4.5 W of idler light at 2896nm is obtained. A tuning range of idler light from 2688nm to 3016nm is achieved, within which the highest optical-optical conversion ettlciency from pump power to OPO output is 35.1%. Moreover, a signal light of -500mW from 1644 to 1700nm with a repetition rate of 233.8 MHz is generated.

Efficient Pumping Scheme by Direct Excitation of Upper Laser Level in Nd：CNGG

We report an efficient pumping scheme which involves a direct excitation of the upper lasing level of a four-level laser in a Nd-doped Caa （NbGa）2-x Ga3O12 （Nd：CNGG） by using a tunable Ti：sapphire, 700-920nm, cw pump source. The slope efficiency is improved from 10.5% of the traditional band pumping at 808nm to 21.8% of the direct pumping at 882nm. The influence of pumping wavelength on lasing is discussed. We present a scheme of double pumping for lasing.