Multiple photon laser photochemistry

Ｍｕｌｔｉｐｌｅｐｈｏｔｏｎｌａｓｅｒｐｈｏｔｏｃｈｅｍｉｓｔｒｙ￥Ｖ．Ｓ．Ｌｅｔｏｋｈｏｖ（ＩｎｓｔｉｔｕｔｅｏｆＳｐｅｃｔｒｏｓｃｏｐｙ，ＵＳＳＲＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｔｒｏｉｔｚｋ，ＭｏｓｃｏｗＲｅｇｉｏｎ，１４２０９２，Ｒｕｓｓ...     

Modulation Instability in Non Kerr-like Optical Fibers near the Zero Dispersion Point

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｍｏｄｕｌａｔｉｏｎｉｎｓｔａｂｉｌｉｔｙ（ＭＩ）ｉｎｓｉｌｉｃａｂａｓｅｄｇｌａｓｓｆｉｂｅｒ，ｆｉｒｓｔｐｒｏｐｏｓｅｄｂｙＨａｓｅｇａｗａ［1］，ｒｅｆｅｒｓｔｏａｐｒｏｃｅｓｓｉｎｗｈｉｃｈａｃｏｎｔｉｎｕｏｕｓ...     

Realizing 20 Gbits OTDM Transmission over 50km Truewave Fiber with Dispersion Compensation

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｒｅａｒｅｔｗｏｍｅｔｈｏｄｓｔｏｅｎｈａｎｃｅｔｈｅｃａｐａｃｉｔｙｏｆｔｈｅｔｒａｎｓｍｉｓｓｉｏｎｓｙｓｔｅｍ：ｏｐｔｉｃａｌｔｉｍｅｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇ（ＯＴＤＭ）ａｎｄｏｐｔｉｃａｌｗａｖｅｌｅｎｇｔｈｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘｉｎｇ（ＷＤＭ）．ＯＴＤＭｉｓｂｅｉｎｇｗｉｄｅｌｙｒｅｓｅａｒｃｈｅｄｂｅｃａｕｓｅｏｆｓｏｍｅｖｉｒｔｕｅｓｉｎｏｐｔｉｃａｌｎｅｔｗｏｒｋｓ［１～４］．ＯＴＤＭｗｉｔｈｔｈｅｓｉｎｇｌｅｃｈａｎ…     

A Simple Method for Designing Diffractive Optical Elements

ＡＳｉｍｐｌｅＭｅｔｈｏｄｆｏｒＤｅｓｉｇｎｉｎｇＤｉｆｒａｃｔｉｖｅＯｐｔｉｃａｌＥｌｅｍｅｎｔｓＭ．ＺｈｏｕＤ．Ｌｉｎ（ＳｔａｔｅＫｅｙＬａｂｏｆＯｐｔｉｃａｌＴｅｃｈｎｏｌｏｇｉｅｓｏｎＭｉｃｒｏｆａｂｒｉｃａｔｉｏｎ，ＩｎｓｔｉｔｕｔｅｏｆＯ...     

Emission Spectrum of Two Atoms in Two-mode Multiphoton Raman Coupled Model

ＥｍｉｓｓｉｏｎＳｐｅｃｔｒｕｍｏｆＴｗｏＡｔｏｍｓｉｎＴｗｏ－ｍｏｄｅＭｕｌｔｉｐｈｏｔｏｎＲａｍａｎＣｏｕｐｌｅｄＭｏｄｅｌ￥ＦＥＮＧＪｉａｎ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ，ＬｉａｏｃｈｅｎｇＴｅａｃｈｅｒ＇ｓＣｏｌｌｅｇｅ，Ｓｈａｎｄ...     

半导体超晶格的多声子拉曼散射研究

半导体超晶格的多声子拉曼散射研究／张树霖，杨昌黎，侯勇田（北京大学物理系北京１００８７１）彭中灵，李杰，袁诗鑫（中科院上海技物所上海２０００８３）Ｒ．Ｐｌａｎｅｌ（ＭｉｃｒｏｓｔｒｕｃｔｕｒｅｓａｎｄＭｉｃｒｏｅｌｅｃｔｒｏｎｉｃｓＬａｂｏｒａｔｏｒ...     

High Speed Demultiplexer Based on a Three-Wavelength SLA

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｏｒｄｅｒｔｏｍｅｔｔｈｅｈｉｇｈｂａｎｄｗｉｄｔｈｒｅｑｕｉｒｅｍｅｎｔｉｎｏｐｔｉｃａｌｔｉｍｅｄｉｖｉｓｉｏｎｍｕｌｔｉｐｌｅｘ（ＯＴＤＭ）ｔｅｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓｙｓｔｅｍｓ，ｔｈｅｓｉｇｎａｌｍｕ...     

评述文章扫描(英文)

１ＴｈｅｏｒｙｏｆＢｏｓｅ－Ｅｉｎｓｔｅｉｎｃｏｎｄｅｎｓａｔｉｏｎｉｎｔｒａｐｐｅｄｇａｓｅｓ（ＦｒａｎｃｏＤａｌｆｏｖｏ,ＳｔｅｆａｎｏＧｉｏｒｇｉｎｉ,ＬｅｖＰ．Ｐｉｔａｅｖｓｋｉｉｅｔａｌ．Ｒｅｖ．Ｍｏｄ．Ｐｈｙｓ．,１９９９,７１：４６３—５１２）２Ｔｏｐ－ｑｕａｒｋｃｏｎｄｅｎｓａｔｉｏｎ（Ｇ．Ｃｖｅｔｉｃ．Ｒｅｖ．Ｍｏｄ．Ｐｈｙｓ．,１９９９,７１：５１３—５７４）３ＰｒｅｃｉｓｉｏｎｔｅｓｔｓｏｆｔｈｅｅｌｅｃｔｒｏｗｅａｋｉｎｔｅｒａｃｔｉｏｎａｔｔｈｅＺｐｏｌｅ（Ｍ．Ｍａｒｔ…     

Pedestal Measurement of Laser Pulses

ＰｅｄｅｓｔａｌＭｅａｓｕｒｅｍｅｎｔｏｆＬａｓｅｒＰｕｌｓｅｓＷＡＮＧＹｉｍｉｎＺＨＡＮＧＺｈｅｎｇｑｕａｎＸＵＺｈｉｚｈａｎ（ＳｈａｎｇｈａｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓ＆ＦｉｎｅＭｅｃｈａｎｉｃｓ，ＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅ...     

Laser Trasformation Hardening for Material as Mud Pump Liner

ＬａｓｅｒＴｒａｓｆｏｒｍａｔｉｏｎＨａｒｄｅｎｉｎｇｆｏｒＭａｔｅｒｉａｌａｓＭｕｄＰｕｍｐＬｉｎｅｒＴＡＮＧＦｕｒｏｎｇ；ＭＡＤｅｙａｎ；ＰＥＮＧＳｈｅｎｇｓｈａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，ｓｏｕｔｈ...     

Analysis of the conditions favoring the onset of long-range order in disordered relaxors of different types

The possibility of realizing a stable relaxor behavior in PbSc_1/2Nb_1/2O₃ (PSN) compounds and the conditions favoring the formation of a phase with long-range order in PbZn_1/3Nb_2/3O₃ (PZN) are studied using optical methods. It is found that the replacement of only 6% of Pb ions with Ba ions (PBSN-6) freezes the relaxor state in PSN compounds, while adding even 7% of PbTiO₃ to the PZN relaxor (PZN-7PT) leads to the formation of a phase with long-range order and a phase transition occurring at T _maxε through the percolation mechanism. Common features in the formation and destruction of the long-range order phase in relaxors of different types are revealed. The differences associated with the presence of spontaneously polarized ferroelectric regions in the cubic nonpolar matrix of PSN-type compounds are determined.     

Piezoresponse imaging and local characterization of ferroelectric domains in Pb(Zn1/3Nb2/3)O3–7%PbTiO3 single crystals

Ferroelectric domain structures of (001)‐oriented Pb(Zn_1/3Nb_2/3)O₃–7%PbTiO₃ (PZN‐7%PT) single crystals were visualized and characterized by piezoresponse force microscopy (PFM). Locally regular domain configurations are found to be possibly related to the stable macroscopic properties in the PZN‐7%PT single crystals. Nanoscale piezoresponse hysteresis loops measured by PFM tip revealed no evidence of local domain switching behavior in the PZN‐7%PT single crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Antiferroelectric–ferroelectric phase transition in lead zinc niobate modified lead zirconate ceramics: crystal studies, microstructure, thermal and electrical properties

The combination of antiferroelectric PbZrO₃ (PZ) and relaxor ferroelectric Pb(Zn_1/3Nb_2/3)O₃ was prepared via the columbite precursor method. The basic characterizations were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), linear thermal expansion, differential scanning calorimetry (DSC) techniques, dielectric spectroscopy, and hysteresis measurement. The XRD result indicated that the solid solubility limit of the (1−x)PZ–xPZN system was about x=0.40. The crystal structure of (1−x)PZ–xPZN transformed from orthorhombic to rhombohedral symmetry when the concentration of PZN was increased. A ferroelectric intermediate phase began to appear between the paraelectric and antiferroelectric phases of pure PZ, with increasing PZN content. In addition, the temperature range of the ferroelectric phase increased with increasing PZN concentration. The morphotropic phase boundary (MPB) in this system was located close to the composition, x=0.20.     

Ferroelectric properties of Pb(Zr1/2Ti1/2)O3–Pb(Zn1/3Nb2/3)O3 ceramics under compressive stress

Effects of compressive stress on the ferroelectric properties of ceramics in PZT–PZN system were investigated. The ceramics with a formula (1−x)Pb(Zr_1/2Ti_1/2)O₃–xPb(Zn_1/3Nb_2/3)O₃ or (1−x)PZT–(x)PZN (x = 0.1–0.5) were prepared by a conventional mixed-oxide method. The ferroelectric properties under the compressive stress of the PZT–PZN ceramics were observed at the stress levels up to 170 MPa using a compressometer in conjunction with a modified Sawyer–Tower circuit. It was found that with increasing compressive stress the area of the ferroelectric hysteresis (P–E) loops, the saturation polarization (P_sat), the remnant polarization (P_r), and the coercive field (E_c) decreased. These results were interpreted through the non-180° ferroelastic domain switching processes.     

Reverse dependences of the permittivity of xPZN − (1 − x)PSN ferroelectric ceramics on the bias electric field

The effect of bias electric fields E ₌ on the dielectric response of xPZN ? (1 ? x)PSN ferroelectric solid solutions with PZN contents x = 0, 0.05, 0.20, and 0.50 is investigated in the temperature ranges corresponding to the smeared phase transitions of the studied compounds. It is concluded that an increase in the PZN content in this system leads to a narrowing of the temperature range of existence of the relaxor phase.     

Elastic–plastic deformation of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 single crystals during nanoindentation

The elastic–plastic deformation behavior of (001)- and (011)-oriented single crystal solid solutions of Pb(Zn_1/3Nb_2/3)O₃–(6–7)% PbTiO₃ (PZN–PT) have been studied using a nanoindentation technique. A procedure is presented here to isolate the elastic, elastic–plastic and plastic contributions to the deformation using the unloading data, and a parameter, referred to as relaxation, is defined to characterize the elastic–plastic deformation during nanoindentations. This relaxation parameter increases with the maximum indentation load due to the higher indentation stress induced, and it also causes less recovery of the material upon indentation unloading compared to predicted pure elastic recovery. For a (001) surface, the relaxation value remains virtually unchanged within the range of the maximum indentation load of 10–50 mN, possibly due to a complete localized depoling of the non-180° domain switching. It is also found that the unpoled surface is more prone to stress-induced depolarization compared to the poled surfaces. Furthermore, by applying the continuous stiffness measurement (CSM) technique, the effects of multiple loading/unloading are studied for both (001)- and (011)-oriented PZN–PTs using the maximum indentation loads of 20 and 50 mN. With more loading/unloading cycles at higher CSM frequencies, stress-induced depolarization becomes prevalent and the contribution of the domain reorientation towards elastic recovery is significantly reduced. As a consequence, the relaxation value is increased, indicating more elastic–plastic deformation. This CSM effect is especially pronounced for poled (011) surfaces.     

xPMnS-(1－x)PZN陶瓷的相变特性研究

研究了xPMnS-(1-x)PZN 四元系压电陶瓷的相变特征，分析了组成变化对材料相变特性的影响.结果表明，xPMnS-(1-x)PZN陶瓷具有弥散性相变特点，在相变过程中存在明显的介电热滞.电子结构计算结果表明，弥散相变的原因是由于不同B位原子与周围氧原子成键强度不同所致.当x值较大(或较小)时具有弛豫铁电体特征，相变弥散性较强；当组成位于x=0.4附近时具有正常-弛豫铁电体特征，相变的弥散性较弱. 关键词： xPMnS-(1－x)PZN 弥散相变 介电热滞     

The improvement in dielectric and ferroelectric performance of PZT–PZN ceramics by thermal treatment

Pyrochlore-free lead zirconate titanate – lead zinc niobate ceramics have been systematically investigated in the as-sintered condition as well as after annealing. The ceramics were characterized by dielectric spectroscopy and Sawyer–Tower polarization (P–E) measurements. The powders of Pb[(Zr_1/2Ti_1/2)_(1−x)–(Zn_1/3Nb_2/3)_x]O₃, where x = 0.1, 0.3 and 0.5 were prepared using the columbite–(wolframite) precursor method. The general trend seems to indicate that the annealed samples become more normal-ferroelectric-like behavior as opposed to the relaxor-ferroelectric-like behavior observed in the as-sintered state. The as-sintered 0.9PZT–0.1PZN ceramic exhibited weak relaxor-ferroelectric behavior, with a relatively low dielectric constant maximum of 14,000 measured at 1 kHz. Annealing resulted in a transition to normal-ferroelectric-like behavior, a shift in the dielectric maximum temperature from 360 °C to 350 °C, and a dramatic increase in the dielectric constant at 1 kHz to a maximum value of 35,000 for the longer anneal. After thermal annealing at 900 °C for one week a strong enhancement of remanent polarization (P_r) was observed.     

高功率二极管激光器相变冷却技术

根据高功率二极管激光器的散热需求,设计了一种储能式相变冷却实验系统,并开展了喷雾相变冷却器和微通道相变冷却器的设计。采用多孔微结构的换热表面,用氨做制冷剂,实现了喷雾相变冷却器表面温度37 ℃时,散热功率密度达到了511 W/cm2。采用节流汽化原理,分别设计了背冷式相变微通道冷却器和薄片型的模块式相变微通道冷却器,背冷式相变微通道冷却器采用氨做制冷剂, 散热功率密度达到了550 W/cm2,采用R124做制冷剂,散热功率密度约270 W/cm2。采用R124做制冷剂,实现了脉冲激光功率3 kW和连续激光功率100 W的相变冷却二极管激光器模块封装。     

Mean-Field Studies of a Mixed Spin-3/2 and Spin-2 and a Mixed Spin-3/2 and Spin-5/2 Ising System with Different Anisotropies

The magnetic properties of a mixed spin-3/2 and spin-2 and a mixed spin-3/2and spin-5/2 Ising ferromagnetic system with different anisotropies are studied by means of mean-field theory (MFT). The dependence of the phase diagram on single-ion anisotropy strengths is studied too. In the mixed spin-3/2 and spin-2 Ising model, besides the second-order phase transition, the first order-disorder phase transition and the tricritical line are found. In the mixed spin-3/2 and spin-5/2 Ising model, there is no first-order transition and tricritical line.