Crystal Growth and Structure of Novel Tolane Nonlinear Optical Materials

A novel tolane 4-methoxy-4'-nitro-diphenyl-acetylene (MONA) has been prepared quantitatively by reacting cuprous p-methoxy phenyl-acetylene with p-iodonitrobenzene. A single crystal of the Moan was grown by solution growth method. The crystal was then characterized by X-ray diffraction structure analysis and second-harmonic generation(SHG)investigation. Polymorphous crystal forms of the MONA were grown from different solvents having different nonlinear optical properties depending on their different crystal structures. The relationship between the crystal growth and crystal structure is discusse.

Thermal and Transmission Properties of UV Nonlinear Optical Material——ZnCd(SCN)_4 Crystal

zinc cadmium thiocyanate (ZCTC), ZnCd(SCN)_4, has been discoveredas a UV second-order nonlinear optical coordination crystal. Titsthermal and transmission Properties are reported. The thermaldecomposition is characterized by using the X-ray Powder diffraction(XRPD) and infrared (IR) spectroscopy at room temperature. TheAbsorptions of intrinsic ions and ZCTC in a solution state arediscussed as well as Transmission properties of the ZCTC crystal. Aneffective method of reducing the surface Reflection loss of ZCTCcrystal is introduced.

Influence of Metallic Substitutions on the Optical and Mechanical Properties of NLO Benzoyl Glycine Crystals

Benzoyl glycine （BG） is a promising organic nonlinear optical （NLO） crystal, whose second harmonic generation （SHG） efficiency is much higher than that of KDP （potassium dihydrogen phosphate）. Single crystals of pure, Cu2＋ and Cd2＋ doped BG were grown by slow evaporation technique. Optically transparent and defect free single crystals of size up to 10 mm×15 mm×10 mm were harvested in a period of 40-60 days. The growth conditions of pure and doped crystals of BG were optimized and the grown crystals were confirmed by single crystal XRD （X-ray diffraction）. The grown crystals were characterized by FTIR （Fourier transform infrared spectroscopy）, optical absorption and microhardness studies. The microhardness studies confirm that BG has a moderate VHN （Vickers hardness number） value in comparison to the.other organic NLO crystals. The efficiency of frequency doubling was measured for the using Nd：YAG laser and the results were discussed.

ORGANIC NONLINEAR OPTICAL CRYSTAL:N-(4-NITROPHENYL)-(s)-(+)-2-PYRROLIDINEMETHYLENE TOSYLATE(NPP-OTs)

Large crystal NPP-OTs has been obtained by growth from solution,its powder SHG efficiency is 1/3 of urea.It shows it is a new convenient approach to obtain organic second-order NLO crystal:the dipole-dipole interaction is oppos- ed by introducing a large side group.

New Complex Nonlinear optical Crystal-Bis(4-methoxybenzaldehyde thiosemicarbazone) Zinc Chloride(ZnL_2Cl_2)

The structure of ZnL2Cl2 (L=4-methoxybenzaldehyde thiosemicarbazone) has beenobtained by x-ray diffraction. The compound crystallized in space group Cc with Z=4, in a unit cellof dimensions, a=9.08909(10), b=22. l420(10), c=11 .7890(l0)A,β=90.050(10)°, v=2374.6(12)A3,Dc=1 .552gcm-3. H=1 .463mm-1. R=0.0338. and Rw=0.0418. The structure contains individualZnL2Cl2 distorted tetrahedral units in which L molecules are S-bonded as monodentate to the metalions; chloride ions are also coordinated. The nonlinear optical properties of the zinc complex arealso presented in this letter.

Recent Developments in Functional Crystals in China

Functional crystals are the basic materials for the development of modern science and technology and are playing key roles in the modern information era. In this paper, we review functional crystals in China, including research history, significant achievements, and important applications by highlighting the most recent progress in research. Challenges for the development of functional materials are discussed and possible directions for development are proposed by focusing on potential strengths of these materials.

Deep-ultraviolet nonlinear optical crystals by design:A computer-aided modeling blueprint from first principles

Deep-ultraviolet(DUV)nonlinear optical(NLO)crystal is indispensable in current DUV all-solid-state laser technology,which is the key device to generate DUV light by frequency conversion.Due to stringent criteria,DUV NLO crystals are scarce and their discovery faces a big challenge.Although KBe2BO3F2(KBBF)is already excellent for current uses,the development of DUV science requires the materials with shorter output wavelengths and larger NLO effects,so as to meet the needs of DUV lasers with higher precision and higher power.Therefore,how to efficiently design DUV NLO materials has always been the core issue in NLO materials science.Looking back on the development of NLO materials,it turns out that theoretical modeling and simulation is an effective and efficient method,not only for mechanism understandings,but also for experimental exploration.In this article,in order to accelerate the process of DUV materials discovery,we summarize and propose a powerful computeraided modeling system and design blueprint that can be used to evaluate the DUV NLO performance in a faster way than pure experiments.With this in hand,we enrich the understanding of NLO structure-property correlation,and systematically prospect the DUV NLO properties on the basis of many existing and designed structures according to different structural types and chemical compositions.Seven novel structures are predicted for the first time to exhibit potential DUV NLO capabilities.All the results enable us to believe that the computer-aided modeling blueprint will play an important role in the exploration of new DUV NLO crystals.

Evaluating refractive index and birefringence of nonlinear optical crystals:Classical methods and new developments

Nonlinear optical(NLO)materials play an increasingly important role in laser technology.Birefringence is one of the most important parameters for NLO materials to realize angle phase-matching conditions.In comparison with other desirable optical properties,the availability of birefringence and refractive index dispersion is especially problematic owing to the strict requirements for single crystals.In this review,we described how to obtain the refractive index and birefringence of NLO materials from crystals sub-millimeters to centimeters in size.Espe-cially,recently developed methods including the minimum deflection angle method,auto-collimation method,prism coupling method,oil immersion technique,interference color method,and theoretical calculation(DFT)for rapid assessment of birefringence are summarized,the contents of which are mainly focused on the principles and typical applications,together with the advantages and drawbacks.In addition,representative examples of bire-fringent measurements were presented.The purpose of this work is to provide a useful perspective on the characterization of birefringence for NLO materials.It is hoped that this review can give a clear description of the birefringence measurements and accelerate the discovery of new NLO crystals.

Ultraviolet Nonlinear Optical Crystals inπ-Conjugated System

UV nonlinear optical(NLO)crystals are essential materials for UV solid state laser output.To date,frequency conversion in UV region is mainly dependent on borates with planar BO3 or B3O6 units.Since the practical applications require more and more high comprehensive properties of crystals,it is urgent to develop new UV NLO crystals.However,it is more and more difficult to find new borate NLO crystals because borate NLO crystals have been studied for several decades.Therefore,it is important to search new systems for the exploration of UV NLO crystals.Based on the relationship between the microstructure and properties of the groups,we proposed that inorganic(CO3)2-and(NO3)-groups can be as new NLO active units for UV NLO crystals because they haveπ-conjugated configuration.Accordingly,our group have performed related work in carbonate and nitrate systems in recent years,which resulted in finding some excellent carbonates and nitrates NLO crystals.In addition,we have recently expanded the research field from inorganic to organicπ-conjugated systems,such as isocyanurates.This mini review will introduce the research results of our team in the field of UV NLO crystals including carbonates,nitrates and cyanurates in recent years.

Properties of second harmonic generation in nonlinear optical crystals CsLiB_6O_(10) and K_2Al_2B_2O_7

The phase-matching for nonlinear optical crystal, the nonlinear phase matching angle, effective nonlinear coefficient, walk-off angles, permitted angle, and permitted wavelength are obtained in type-I and type-II phase matching in ultraviolet （UV） nonlinear optical crystals CsLiB6O10 （CLBO） and K2Al2B2O7 （KABO） by detailed theoretical simulation. Through analysis and comparison, the phase matching characteristics of the second harmonic generation in the crystals are discussed when the wavelengths of the basic frequency lights turn continually.

Research progress on mid-IR nonlinear optical crystals with high laser damage threshold in China

Nonlinear optical(NLO)crystals have been playing an increasingly important role in laser science and technology.The NLO crystals used in the middle infrared(mid-IR)region,compared with the NLO crystals in the other wavelength regions,are still not good enough for the application of high-energy laser.The main defect is that their laser damage thresholds(LDT)are low.Chinese scientists have made a lot of important contributions to the UV and visible NLO crystals.In the last decade,they also did a lot of work on the mid-IR NLO materials.The main purpose of these researches is to increase the LDT and simultaneously balance the other properties.This paper presents a brief summary of their research progress in this topic on three types of materials:chalcogenides,oxides,and halides.The emphasis is put on the design strategy and quality control of the crystals.

掺锶的偏硼酸钡(Sr_xBa_(1-x)B_2O_4)大块单晶的生长和表征

Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an excellent NLO cryst al for UV region,while the high temperature one (α BBO) is known as a good bir efringent material.α BBO crystal possesses better transparency in the ultravio let region compared with commonly used YVO 4 and CaCO 3 crystals.However,due t o phase transition problem,it is difficult to grow single α BBO crystals by D CZ method,which restricts its wider application.α BBO crystal usually cracks upon cooling resulted from phase transition to β phase.Therefore,it is difficult to grow β BBO single crystals directly from pure BaB 2O 4 mel t;however,to grow single crystals of α BBO is not easy,either. Our recent experiments showed that one could avoid cracking of α BBO cryst als by Sr 2+ doping.This minute amount of Sr 2+ plays the role of structure stabilizer,which inhibits structural reconstruction. In this way,Sr 2+ d op ed BBO single crystals do not subject to phase transition from 925℃ down to roo m temperature. We have mow successfully grown out α BBO single crystals 30mm in diameter by D CZ method from Sr x Ba 1- x BO 4 melt with Sr concentration 0.3 0 .5%.The ratation rate is 10 15r/min,pulling speed is 1 2mm/h.Preliminary tests revealed that its structure and physic chemical properties were almost identic al to those grown from pure melts.These Sr 2+ doped α BBO crystals are no w being widely used in optical isolators.

功能晶体材料CMTD生长动力学和结晶习性的研究

Process of crystal growth can be controlled by both surface kinetics and by volume transport as well.Although the complicated relation between the surface kinetics and volume transport exsits,generally,they are studied seprately.Due to the mathematical complexity of heat and mass transport equations,the in depth studies of heat and mass transport process become difficult.Most of the studies on the transport were performed for the growth from melt.Most of the work on Surface kinetics has been done for crystal growth from aqueous solution because the in situ observation of crystal growth is easily carried out.In recent years,the surface kinetics studies on the nanometer scale,even atomic scale,are demonstrated by using AFM.

阴离子杂质对KDP晶体生长习性的影响及快速生长研究

Great interest is being focused on the growth technique of KDP crystal,the first choice material for the fabrication of frequency converter and electro optic switcher used in the studies of inertial confinement fusion (ICF).To reduce the cost of growth,scientists are endeavoring to promote the growth rate.The“point seed” method is one of rapid growth techniques recently developed by Lawrence Livermore National Laboratory.In the former technique,crystals are grown in all three directions at an averaged rate of 10 15mm/day. Impurities are regarded as one of the factors to inhibit the growth rate.It is generally accepted that high valence cationic ions,such as Fe 3+ ,Cr 3+ ,Al 3+ ,etc,are easy to be adsorbed on the prismatic faces and inhibit their growth.Some anions,especially those have ability to form strong hydra bond,such as phosphate derivatives (polyphosphate,metaphosphate,pyrophosphate,etc) have significant inhibiting effects on the growth of KDP pyramidal face.It is suggested that the H bonding is the key interaction force between the growing surface and the impurities.

熔盐法生长Ca_4GdO(BO_3)_3单晶

Ca 4GdO(BO 3) 3 (GdCOB) single crystal is a new nonlinear optical crystal whi ch was discovere d in recent years.It has a large effective nonlinear optical coefficient,a high damage threshold,good chemical and physical properties and insensitivity to moi sture.Its moderate birefringence is favorable for phase matching.These propertie s make it possible to obtain frequency doubling laser of 1.064μm.By doping,it may be a excellent self frequency doubling crystal.Transparent single crystals GdCOB as needle were grown by the flux method. Chemical compounds Gd 2O 3,CaCO 3,B 2O 3 and H 3BO 3 were used as starti ng materials.By many experiments,with different ratio,it is proper to mix the st arting materials according to the reaction Gd 2O 3+8CaCO 3+6H 3BO 3=2 Ca 4 G dO(BO 3) 3+8CO 2+9H 2O.PbO was used as the main flux ,adding moderate PbF 2 , and B 2O 3.B 2O 3 also can be used as initial compounds and it is also a goo d solvent,but at high temperature,it has heavy viscousness.The crystals grown fr om B 2O 3 commonly has inclusion,so we used H 3BO 3 instead of B 2O 3.At t he same time,we considered that at high temperature H 3BO 3 will be decomposed and evaporated,which would make the initial composition change.When proper B 2 O 3 was added,it not noly can be used as solvent,but also can stabilize solvent component.The melt was contained in a platinum crucible.After holding the melt 1200℃ for 24h,it was cooled at a rate of 0.5℃ per hour.Single crystals GdCOB were obtained.With microscope,we observed the crystals have defects such as inc lusion and bubbles,which are related to rapid cooling,imperfect melt transport a nd unstable temperature.

非线性光学晶体K_(3.0)Li_(2.0)Nb_(5.0)O_(15.0)的生长

Potassium lithium niobate single crystal with a dimension of 20mm×15mm×30mm was grown by EFG technique in our laboratory.Compared with Czochralski method for the growth of KLN crystals,EFG technique possesses the following merits.Crack of crystals can be weakened during the lowering of temperature and the crystals free of crack can be obtained.The crystals have no rotation,the growth striation caused by the rotation of the crystals can be eliminated.With action of capillary from a die hole,the convective effect of melt at solid liquid interface can be reduced,therefore the homogeneity of crystals is better than that of crystals obtained by Czochralski method.The growth striation parallels each other and is perpendicular to the growth direction,so the good blue SHG can be obtained when ground wave goes through the KLN crystals.Since capillary force does not fully counteract the convective effect,the inhomogeneity of crystals can’t completely be eliminated.The low SHG conversion efficiency of KLN crystals is mainly caused by inhomogeneneity of crystals.For the growth of incongruent melting crystals,the growth rate is limited by the rejection of impurity,this also makes homogeneity of composition become bad.In the growth of KLN crystals by EFG technique,the fluctuation of the temperature at solid liquid interface should be enough small,and the film thickness of melt should be proper.Too thick film of melt makes the process of crystal growth unstable;too thin film of melt can lead to the constitutional supercooling.

新型深紫外非线性光学晶体的探索

Based on anionic group theory,a computer assisted nonlinear optical(NLO)crystal design system has been developed.This method has proved to be a highly efficient means of discovering NLO crystals.With the help of this system,a series of new borate crystals,like as KBe 2BO 3F 2(KBBF),Sr 2Be 2B 2O 7(SBBO),Ba 2Be 2B 2O 7(SBBO),BaAl 2B 2O 7(BABO)and K 2Al 2B 2O 7(KABO)have been discovered.Among them KBBF possesses the shortest SHG wavelength output,SBBO has the largest SHG coefficient and KABO is found to have the best optical homogeneity and easy to grow out large size of the crystal.The investigation showed that KABO is a promising NLO crystal for 4 th and 5 th harmonic generations of Nd∶YAG laser.

非线性光学晶体电光快速调谐光参量器件的研制

Optical parametric lasers widely using in many science and technology field owin g to its merit of wide tunable spectrum range.But common optical parametric lase rs achieve tune by change of angel or temperature.The tune velocity and tune pre cision of these tune modes does not satisfy in many applications.The reporting i nto an optical parametric laser which achieve tune by electooptic effect,that have got speediness tune velocity and relatively quite tune precision. The optical parametric device design based on parametric fluorescent produce thr ough sum frequency phase matching in nonlinear optical crystals.It is a tune pr o cess of refractive index about parametric and pump light in nonlinear optical cr ystals namely.But refractive index of nonlinear optical crystals possess electro o ptic effect can change via apply transformable electro field.This change only w a nts a time of ns grade.So optical parametric device with nonlinear optical cryst als possess suitability electrooptic effect can realize speediness tune in princ iple.The idea about design on the recommended device here is somewhat as follows .The tune model is phase tuning.To strive increase the effect of electro optic f unction under keep immovable polarization directions of 3 wavelength in the opti cal parametric process,to strive convenient for apply electro field,the electro field is only sensitive for a refractive index of some wavelength in specificall y spectrum region.The principium examination has showed that the idea is reasona ble.Our count have show also that its tune precision same as expectance.

Enhanced nonlinear optical functionality in birefringence and refractive index dispersion of the deep-ultraviolet fluorooxoborates

As a promising candidate,the fluorooxoborate has enkindled new explorations of nonlinear optical materials to meet the deep-ultraviolet criteria.However,big challenges and open questions still remain facing this exciting new field,especially the birefringence and dispersion of refractive index which are fundamental parameters for determining the phasematching second harmonic generation wavelength.Here we designed possible anionic groups in fluorooxoborates,and analyzed the optical anisotropy to check its influence on birefringence,which was proved further by the response electronic distribution anisotropy approximation.The functional modules modulating birefringence in fluorooxoborates were explored systematically.We developed an approach for evaluating the behavior of the refractive index dispersions and found that the fluorooxoborates had small refractive index dispersions owing to the introduction of fluorooxoborate modules.Our results demonstrate that fluorooxoborates can be utilized to realize short phase-matching wavelength markedly and offer a path toward novel performance-driven materials design.