Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences
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Phase Matching Using the Linear Electro-Optic Effect
No full textNational Natural Science Foundation of China [11204327, 11304332]Phase matching is a necessary condition for achieving high-efficiency optical-frequency conversion. To date, practical means of accomplishing phase matching in homogeneous crystals remain limited, despite considerable efforts. Herein, we report a new class of methods aimed at achieving quasiperfect phase matching, based on controllable birefringence produced via the linear electro-optic effect, termed "voltage-tuning phase matching." The wave vectors of the induced polarization and the generated fields can be matched and maintained along the direction of propagation by introducing an external electric field. We analyze the validity and feasibility of this method theoretically and demonstrate it experimentally by applying the linear electro-optic effect and fourth-harmonic generation simultaneously in a partially deuterated KH2PO4 crystal. Quasiperfect phase matching is achieved systematically over a temperature range of the initial phase-matching temperature +/- 2 degrees C. Moreover, this method can overcome the limitation of the birefringence in traditional technologies and provides new functionalities for conventional nonlinear materials as well as low-birefringence and isotropic materials. This technology may significantly impact the study of optical-frequency conversion and has promise for a broad range of applications in nonlinear optics
Co-precipitation synthesis of lutetium aluminum garnet (LuAG) powders: The influence of ethanol
No full textNational Nature Science Founds of China [61378069, 61405221]; Youth Innovation Promotion Association of CASAluminum Garnet (LuAG) precursors were co-precipitated by using ethanol water as the precipitant solvent. The effect of different volume ratios of ethanol to water (R) on the preparation of pure-phase LuAG powders has been mainly studied. The evolution of phase, composition and micro-structure of the as-synthesized LuAG powders were characterized by TG/DTA, FTIR, XRD, BET, and SEM. The BET equivalent diameter of LuAG nano particles increased with R. The ethanol water solvent does not change the main composition of the LuAG precursors, but has great influence on the morphology of the final LuAG nano particles. Uniformly dispersed LuAG powders calcined at 1200 degrees C for 3 h with a particle size of approximately 120 nm were obtained by using ethanol water solvent with proper R = 1. The mechanism of ethanol in the preparation process was discussed
High-precision measurement of optical constants of ultra-thin coating using surface plasmon resonance spectroscopic ellipsometry in Otto-Bliokh configuration
No full textNational Key Research and Development Project of China [2016YFE0104300]; International Science & Technology Cooperation Program of China [2012DFG51590]; Italian-Chinese Project of Great Relevance [PGR00799]In this paper, a surface plasmon resonance (SPR) spectroscopic ellipsometry, based on Otto-Bliokh configuration. is developed for the measurement of thickness and optical constants of ultra-thin coatings. This technique combines sensitivity of surface plasmon with accessibility of optical constants and other advantages of ellipsometry. Surface plasmons (SP) are generated in the sample under test in total reflectance mode and SP geometric distribution over the sample surface is influenced by the coating thickness and optical properties on one hand, and by the air gap thickness on the other hand. Nanoscale control of the thickness of the air gap between a convex surface and the sample was assured using a micron-size beam spot irradiating the contact zone. The amplitude and phase change induced by SPR in the visible and near-infrared spectral range were obtained to determine the dispersion of optical constants and the thickness of the ultra-thin layer. The extracted optical constants were found to be in excellent agreement with the results obtained using TEM and XRR techniques. Both theoretical analysis and experimental results demonstrated high sensitivity and precision of the proposed technique for the analysis of coatings of both metals and dielectrics on metals. (C) 2017 Optical Society or Americ
Ultrafast Saturable Absorption of Core/Shell Colloidal Quantum Dots
No full textNSFC [61378074, 61475173, 61308034, 61575164]; Shanghai Rising-Star Program [14QA1404000]; Youth Innovation Promotion Association of Chinese Academy of SciencesUltrafast saturable absorption (SA) materials that are capable of blocking the optical absorption under strong excitation have extensive applications in photonic devices. This work presents core/shell colloidal quantum dots (CQDs) which have the quantized energy levels, excellent band gap tunability, and possess significant SA performance. When the band gap is close to the pump pulse energy, the CQDs show significant resonant SA response. At the same excitation conditions, the core/shell CQDs dispersions show better SA response than graphene dispersions, and comparable to the recently reported molybdenum disulfide. The carrier dynamics of the SA of the CQDs is analyzed systematically. The research has also found that the two-photon absorption of the CQDs show nearly cubic power law of the band gap, while the SA performance keeps almost the same in the nonresonant regime. Further, superior passive Q-switched laser behavior is observed using the CQDs as a saturable absorber. The results directly reveal the physical processes of this basic problem and broaden the applications of CQDs in photonic devices
Combined spectroscopic analysis of stratified glass eye beads from China dated to the Warring States Period
No full textNational Natural Science Foundation of China [11374314, 51402326]We herein report the application of a combined spectroscopic approach for the analysis of eight stratified glass eye beads unearthed from China, which was dated back to the Warring States Period (475 BC to 221 BC). Portable X-ray fluorescence spectrometry (pXRF) was used to determine that seven samples were typical natron type soda-lime-silicate glass beads with low contents of MgO and K2O except for one plant-ash type soda-lime-silicate sample. In addition, combined with micro-Raman spectroscopy, two different types of colorants were present in these beads, namely oxidized transition metals such as Co, Cu and Fe, and antimony-based compound opacifiers/colorants. Furthermore, the distribution of their glassy and scattering phases could be determined by the optical coherence tomography (OCT) images, in which it exhibits that their morphologies were related to their Sb contents. According to the determined typology, chemical composition, micro-crystal, and eyeball structural characteristics within the samples, the possible relations among them were speculated. It is the most interesting finding that seven natron type soda-lime glasses could be imported from the eastern Mediterranean area and one plant-ash type glass could be imported from the eastern region of the Euphrates River such as Iran area. Finally, through comparison with similar contemporary beads excavated from the famous tomb of Marquis Yi of the Zeng State(similar to 433 BC) in the Hubei Province, provenance studies of these beads were carried out, and their origins and relationships are discussed briefly
Silicon carbide doped Sb2Te3 nanomaterial for fast-speed phase change memory
No full textNational Key Basic Research Program of China [2011CBA00607, 2011CBA00602]; National Natural Science Foundation of China [61076121, 61504157, 51472258, 51672292, 61627826, 61137002]In this study, doping of Sb2Te3 with silicon carbide has been proposed to enhance the optical and electrical properties of Sb2Te3. The silicon carbide-doped Sb2Te3 (Sb2Te3-SiC)-based phase change memory cell can be triggered by a 10 ns electric pulse, indicating its excellent electrical properties. Furthermore, ferntosecond pulses are used to study the reversible phase transition processes. The large reflectivity ratio of Sb2Te3-SiC is beneficial for achieving distinguishable logical states in optical applications. X-ray diffraction and transmission electron microscopy results show the SiC doping plays an important role in refining the grain size of Sb2Te3, producing smaller grain. (C) 2017 Elsevier B.V. All rights reserved
The effect of rigid phenoxyl substituent on the NH3-sensing properties of tetra-alpha-(4-tert-butylphenoxyl)-metallophthalocyanine/reduced graphene oxide hybrids
No full textNational Natural Science Foundation of China [51202061, 51002046]; Natural Science Foundation for the Returned Overseas Scholars of Heilongjiang Province [LC2012C02]; Natural Science of Heilongjiang Province [B201308]; Postdoctoral Science-Research Developmental Foundation of Heilongjiang Province [LBH-Q11015]; Innovative Talents Program for the Returned Overseas Scholars of Harbin [2012RFLXG031]; Opening Project Foundation of Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang University), Ministry of EducationHerein, we report a type of enhanced ammonia (NH3) sensing materials formed by the functionalization of reduced graphene oxide (RGO) with 1,8,15,22-tetra-(4-tert-butylphenoxyl)-metallophthalocyanine (TBPOMPc, M = Cu, Ni, and Pb) via a solution self-assembly method based on pi-pi stacking interactions. The RGO/TBPOMPc hybrids exhibit excellent sensitivity, high response value, and fast response and recovery at room temperature, especially the RGO/TBPOPbPc sensor. The enhancement of the NH3-sensing performance by TBPOMPc with a rigid phenoxyl-substituted group is attributed to the self-assembly behavior of TBPOMPc molecules. The rigid structure of TBPOMPc effectively prevents the intermolecular aggregation behavior. On the one hand, it expands the specific surface area of the RGO/TBPOMPc hybrids, which is propitious for the physical adsorption and diffusion of NH3 molecules and reduces the response and recovery time. On the other hand, it weakens the electronic interaction between TBPOMPc molecules and results in reducing the resistance of charge transfer from NH3 to TBPOMPc. Moreover, TBPOMPc is beneficial to enhance the sensitivity and selectivity of the RGO/TBPOMPc sensors towards NH3. By contrast, the response of various RGO/TBPOMPc sensors decreases in the order of RGO/TBPOPbPc > RGO/TBPOCuPc > RGO/TBPONiPc. Furthermore, the rigid structure and central metals of TBPOMPc play a critical role in the sensitivity of NH3, as evidenced from the scanning tunneling microscopy, current-voltage characteristics, and electrochemical impedance spectra
The effects of central metals on ammonia sensing of metallophthalocyanines covalently bonded to graphene oxide hybrids
No full textNational Natural Science Foundation of China [51202061, 51002046, 21303030]; Natural Science Foundation for the Returned Overseas Scholars of Heilongjiang Province [LC2012C02]; Natural Science of Heilongjiang Province [B201308]; Research Fund of Heilongjiang Provincial Education Department [12511377, 12521399]; Postdoctoral Science-Research Developmental Foundation of Heilongjiang Province [LBH-Q11015]; Innovative Talents Program for the Returned Overseas Scholars of Harbin [2012RFLXG031]; Opening Project Foundation of Key Laboratory of Functional Inorganic Material Chemistry (Heilongjiang UniCost-efficient, highly sensitive, selective and stable sensing materials play a key role in developing NH3 sensors. Herein, a series of tetra-beta-aminephthalocyanines metal(II) (aPcMs M = Cu, Ni, Co, Fe) have been successfully covalently bonded on the surface of graphene oxide (GO) by a facile amidation reaction. The obtained aPcM-GO hybrids display good dispersibility, which is beneficial to construct uniform sensing devices. The aPcM-GO sensors exhibit excellent sensing performance in terms of sensitivity, reversibility, reproducibility, selectivity and stability, especially the aPcCo-GO sensor which exhibited a response of about 11.6% (50 ppm), a limit of detection as low as 800 ppb, and a recovery time of about as fast as 350 s at room temperature. The enhanced NH3-sensing performance is mainly due to the synergistic effect between aPcM and GO, e.g. the stronger adsorption interaction of aPcM with NH3, the high electrical conductivity of GO, and the fast charge transfer between aPcM and GO. By comparison, the response of aPcM-GO hybrids to ammonia decreases gradually in the following order of Co > Cu > Ni > Fe >> GO, indicating that the central metals play a critical role in gas sensitivity toward NH3, which is further confirmed by first-principle density functional theory
Enormously enhanced upconversion emission in beta-NaYF4:20Yb,2Er microcrystals via Na+ ion exchange
No full textChinese National Natural Science Foundation [61405215, 61505232]; Jiangsu distinguished professor program [SR10900214]Efficient upconversion (UC) microcrystals are important for the development of novel photonic markers, solid-state lasers, displays, etc. Herein, we report on greatly enhanced UC emission in beta-NaYF4:20Yb,2Er microcrystals via a simple ion-exchange reaction. The ion exchange accompanying with an ionic redistribution process is demonstrated. By simply controlling the amount of NaF (0-8.0 mmol), reaction temperature (140-220 A degrees C), and duration (0-144 h), enormous enhancement of the UC emission up to similar to 4200 times is obtained compared with the pre-synthesized beta-NaYF4:20Yb,2Er microcrystals. The decrease of body defects and change of local structure around lanthanide may account for the UC emission enhancement. This method may apply to other UC materials to increase the UC emission efficiency
Luminescence and scintillation of high silica glass containing SnO
No full textNational Natural Science Foundation of China [51272262, 61405215]High silica glasses containing SnO were prepared by sintering solution-doped porous silica glasses. The sample sintered in the CO reducing atmosphere exhibited a strong emission at 400 nm under 269 nm excitation with a lifetime of 11 mu s, and its intensity was much stronger compared to that of the sample sintered in the air atmosphere. Under X-ray excitation, broad radioluminescence ranging from 300 to 600 nm was observed and the maximum integral intensity was 122% of Bi4Ge3O12 (BGO)