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[IEEE 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Lviv-Slavske, Ukraine (2018.2.20-2018.2.24)] 2018 14th International Conference on Advanced Trends in Radioelecrtronics, Telecommunications and Computer Engineering (TCSET) - Nanoengineering of anisotropic materials for creating the active optical cells with increased energy efficiency
摘要： In this paper the state-of-the-art for exploiting the unique physical and chemical properties of crystalline nanomaterials and their possible applications for creating optical cells with increased energy efficiency are discussed. Using a method of growing crystals from a solution the KDP and TGS nanocrystals were grown in the mesopores of the Al2O3 matrix where the direction of growth was discussed. To investigate the developed nanocomposites the X-ray analysis was used and it showed the predominant crystal orientation of the KDP and TGS in the direction [001] which coincides with the direction of the cylindrical pores. Thus, the possibility of growing of the KDP and TGS nanocrystals in the mesopores of the Al2O3 matrix was developed and provides the prospect of creating optical cells with increased energy efficiency.
关键词： X-ray analysis,anisotropic materials,crystalline nanocomposites,nanoporous matrices,Al2O3,nanofiller KDP and TGS
更新于2025-09-23 15:23:52
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Some structural, linear and nonlinear optical characteristics of single KDP crystals influenced by EDTA additive
摘要： Single Potassium Dihydrogen Phosphates (KDP) crystals were successfully grown in pure and 1 mol% Ethylenediaminetetraacetic acid disodium salt (EDTA) added KDP solutions by Sankaranarayanan–Ramasamy method. Their growth was oriented in type I phase-matching direction which is one of two conditions of maximum second harmonic generation efficiency. The elemental compositions of the crystals were determined by EDX analysis. The UV–Vis spectroscopy, FT-IR analysis, X-Ray diffraction, and second harmonic generation studies have been carried out in order to assess the influence of EDTA additive on quality of KDP crystal. EDTA can improve the structural perfection and optical characteristics of the crystal. Especially, this additive helps increase second harmonic generation efficiency of KDP crystal, which is very useful for frequency doublers.
关键词： Second harmonic generation,EDTA,KDP,Nonlinear optics,SR method
更新于2025-09-23 15:21:21
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Realization of high efficiency and low damage machining of anisotropic KDP crystal by grinding
摘要： Potassium dihydrogen phosphate (KDP) is a non-linear material used in various opto-electronic applications including Q-switches, high-speed photography shutters, frequency harmonic generation lens and Pockels cells in the Inertial Confinement Fusion (ICF) devices. KDP belongs to the most difficult-to-cut material, due to its delicate and unique characteristics including the combination of softness with brittleness, anisotropic performances, tendency for deliquescence and sensitivity to temperature change. Single point diamond turning (SPDT) is considered to be the ideal method for machining KDP components. However, the process efficiency is rather low and often accompanied with severe tool wear issues. This paper studies the feasibility using grinding method to remove the surface material of KDP components with high process efficiency and low damage, fulfilling the task of re-aligning the surface orientation to the crystalline axis. The grinding tests were carried out on a common CNC grinder, using resin bonded diamond grinding wheel, whilst the diamond abrasives are coated with Ni-P alloy. The direction of precision grinding was determined by studying the anisotropy of KDP, including its elastic modulus E, Vickers hardness HV and fracture toughness KIC, to reduce the influence of material anisotropy on machining quality. The grinding process parameters were preliminarily determined based on the experimental results investigating the effects of peripheral speed of the grinding wheel, worktable feed rate and grinding depth on the ground surface roughness. The surface defects, surface morphology and sub-surface damage under different process parameters were investigated. Surface roughness Ra ≤ 0.3μm and sub-surface damage depth SSD ≤ 6μm were obtained. The machining efficiency can be improved by nearly ten times using the proposed precision grinding method, producing nearly the same surface quality (Ra ≤ 0.2μm, SSD ≤ 6μm) as that in the axis fixing phase in SPDT.
关键词： KDP crystal,Crystal axis fixing,Machining efficiency,Sub-surface damage,Grinding,Typical impurities embedded
更新于2025-09-23 15:21:01
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Dynamic behavior modeling of laser-induced damage initiated by surface defects on KDP crystals under nanosecond laser irradiation
摘要： the issue of laser-induced damage of transparent dielectric optics has severely limited the development of high-power laser systems. exploring the transient dynamic behaviors of laser damage on KDp surface by developing multi-physics coupling dynamics model is an important way to reveal the mechanism of nanosecond laser damage. In this work, KDP crystals are taken as an example to explore the mechanism of laser-induced surface damage. Based on the theories of electromagnetic field, heat conduction and fluid dynamics, a multi-physics coupling dynamics model is established for describing the evolution of nanosecond damage processes. The dynamics of laser energy transmission, thermal field distribution and damage morphology during nanosecond laser irradiation are simulated with this model. it is found that the enhancement of light intensity caused by surface defect plays an important role in the initial energy deposition and damage initiation of the laser irradiation area. The evolution of temperature field and crater morphology during subsequent laser irradiation is helpful to understand the laser damage process. The feasibility of this model is verified by the morphology information of typical defect-induced laser damage. this work provides further insights in explaining the laser-induced damage by surface defects on KDp crystals. the model can be also applied to investigate the laser damage mechanisms of other transparent dielectric optics.
关键词： laser-induced damage,multi-physics coupling model,nanosecond laser irradiation,KDP crystals,surface defects
更新于2025-09-19 17:13:59
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Characterization of manufacturing-induced surface scratches and their effect on laser damage resistance performance of diamond fly-cut KDP crystal
摘要： Manufacturing-induced defects have drawn more and more attentions to improve the laser damage resistance performance of KDP crystal applied in high-power laser systems. Here, the morphology of surface scratches on diamond ?y-cut KDP crystal is characterized and their e?ect on the laser damage resistance is theoretically and experimentally investigated. The results indicate that surface scratches could lower laser-induced damage threshold (LIDT) by modulating incident lasers and producing resultant local light intensi?cations. The induced maximum light intensity enhancement factors (LIEFs) are dependent on scratch shapes and dimensions. The di?raction e?ects originating from scratch edges are responsible for the strongest light intensi?cation. Even for ultra-precision ?nished KDP surface with scratches that well satisfy the currently applied scratch/dig speci?cation, the induced LIEFs are quite high, indicating that the actual defect dimension allowance should be amended and speci?ed according to the defect-induced LIEFs. The e?ect of scratches on laser damage resistance is experimentally veri?ed by the tested LIDT, which is approximately consistent with the simulation one. The morphologies of laser damage sites further con?rm the role of scratches in lowering LIDT. This work could o?er new perspective and guidance for fully evaluating the performance of ultra-precision manufactured optical materials applied in high-power laser facilities.
关键词： Laser damage resistance performance,KDP crystal,Manufacturing-induced defects,Diamond ?y-cutting,Light intensi?cation
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22–26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Study on laser multi-focus separation technology for thick KDP crystal
摘要： Potassium dihydrogen phosphate (KDP) crystal is an important electro-optic material in various laser system, and belongs to very difficult-to-cut material, especially for thick crystals. In this study, a laser multi-focus separation technology (LMFS) of thick KDP crystal has been developed by skillfully combining femtosecond laser and LMFS optical system. In this way, the uniformity of temperature and thermal stress distributions along crystal thickness and the utilization efficiency of the laser energy are greatly improved. A penetration crack along crystal thickness could be formed and its propagation direction could be controlled to achieve safe and high-quality separation. The separating thickness of LMFS (50 mm) is at least 4 times thicker than that of existing laser separating technology, and the separating efficiency of LMFS (200 mm/s) is at least 20 times faster than that of traditional mechanical method. The generation mechanism of multi-focus was expounded by optical analysis and design, and verified by an established LMFS optical system. A thick KDP crystal with the thickness of 50 mm was separated successfully by LMFS. The quality of the separated sidewall surface was clean and flat (roughness of 10.857 nm, flatness of 3.5389 mm) without any contamination, underground damage and edge fragmentation. The experimental results proved the feasibility of LMFS, and are in good agreement with the theoretical analysis.
关键词： femtosecond laser,KDP crystal,optical system,laser multi-focus separation technology,thermal stress
更新于2025-09-16 10:30:52
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Optical Scheme of Obtaining Highest Transmission Factor in Case of KDP Based Electro-Optic Crystal by the Adjustment of Suitable Biasing Voltage and Number of Feedback Passing
摘要： The electro-optic effect becomes prominent when an electric field is applied across the optic axis of a dielectric material inducing the changes in refractive indices of the medium. Kerr and Pockels cells are massively used as optical switches because of their nonlinear electro-optic character. Potassium di-hydrogen Phosphate (KDP) crystal is a very good electro-optic Pockels material as well as has a good switching behavior in optical and opto-electronic domain. The principle of this electro optic effect can be successfully used to develop optical switch based information processing devices. Transmission co- efficient of the polarized light beam have been modulated in a new way by introducing a multi passing scheme across a electro-optic material. Here transmission co-efficient plays a vital role to examine how much output intensity changes for developing feedback one by one in ascending order. In this paper a novel study for the sizable increase of transmission co-efficient of a KDP crystal for a fixed biasing voltage is reported adopting proper feedback mechanism of light. This paper we also observe an theoretical basis for achieving unit transmission coefficient which minimum amount of voltage require for adopting comparatively many large number of feedback.
关键词： electro-optic effect,amplitude modulation,KDP crystal,transmission co-efficient
更新于2025-09-11 14:15:04
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Research on the Relationship between Cutting Force and Machined Surface Quality in Micro Ball End-Milling of Potassium Dihydrogen Phosphate Crystal
摘要： Potassium dihydrogen phosphate (KDP or KH2PO4) crystal is widely used as terminal frequency converters in inertial confinement fusion (ICF). However, KDP crystal is a typical difficult-to-cut optical crystal with the characteristic of soft-brittle. In this work, the relationship between cutting force and processed surface quality in micro ball end-milling of KDP crystal with various depth of cut and spindle speed is studied by carried out the micro-milling experiments. Fast Fourier Transform (FFT) algorithm is used to diagnose the recorded cutting force. The periodic change of cutting force and the cutting force after filtering noises can be got through FFT analysis. Through calculating the correlation coefficients between the static component of thrust force and roughness value Ra of machined grooves, as well as the peak-valley (P-V) value of thrust force and dimensional error of machined grooves, the roughness value Ra and dimensional error of machined grooves would be predicted by monitoring the static component and P-V value of the thrust force, respectively. The relatively large spindle speed helps to reduce the roughness value Ra. The spindle speed with moderate value is recommended to reduce the dimensional error of machined groove because the dimensional error of machined groove will increase when the spindle speed is small enough (causing brittle cutting) or large enough (reducing cutting stability).
关键词： micro ball end-milling,KDP crystal,cutting force,FFT analysis,machined surface quality
更新于2025-09-10 09:29:36
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Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation
摘要： It has been a tremendous challenge to manufacture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the requirements of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room temperature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nano-scale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load-displacement curves during nanoindentation.
关键词： Dislocation,Potassium dihydrogen phosphate (KDP) crystals,Creep-deformation,Stress
更新于2025-09-09 09:28:46
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Toward the Understanding of KDP Crystal Surface Height Variation by a Rapid Growth Technique
摘要： Numerical simulations are performed to understand the variation of KDP crystal surface height by a rapid growth technique. The theoretical models used in numerical simulations couple the macroscopic transport of solute and impurities with the microscopic interfacial kinetics processes. Studies are specifically made to growth rate fluctuation at each growth interface subject to variations in crystal size, bulk supersaturation, rotation rate of the stirring paddle, and impurities. It is found that predicted interface moving speeds, equivalent to the growth rate, are uniformly distributed normal to each pyramidal and prismatic faces at macroscale by taking into account the interfacial kinetics process; however, they fluctuate wavily at microscale. The amplitude of growth rate fluctuation is on the order of micrometer. The fluctuation in growth rate will cause KDP crystal surface height variation and lead to the formation of micron-sized and nanosized inclusions in the crystals. Increasing crystal size and bulk supersaturation intensifies the fluctuation in the growth rate, which may reduce the quality of grown KDP crystal. Increasing paddle’s rotational speed can make the fluctuation of the growth rate decrease. The impurities influence the growth rate of the KDP prismatic face obviously. When impurities exist in solution, the growth rate of the prismatic face decreases greatly and the fluctuation of the growth rate is enhanced by 1 order of magnitude.
关键词： growth rate fluctuation,numerical simulations,surface height variation,rapid growth technique,KDP crystal,impurities
更新于2025-09-09 09:28:46