高功率飞秒脉冲激光器的进展

概述了超短激光脉冲技术发展的历程。详尽的论述了啁啾脉冲放大技术的原理和一些关键技术 ,并对当今飞秒激光器研究发展的状况进行了综述。在分析其应用前景的基础上 ,进一步指出了这一技术领域未来的发展趋势。结果表明 ,脉冲激光放大系统以后的发展方向是 :更短脉冲 ;追求更高峰值功率 ;连续光谱调谐化 ;向小型化乃至全光纤化发展。     

玻璃中CdSeS纳米晶体的生长及其性能

对掺有镉、硒、硫的玻璃在500—800℃退火2—24h,生长了不同尺寸的CdSxSe1x纳米晶体.用分光光度计和光致发光光谱(PL)分析了纳米晶体的性能.退火温度低于550℃,纳米晶体处于成核阶段,600—625℃处于正常扩散生长阶段,700—800℃处于竞争生长阶段;而650℃处于两种生长阶段之间.虽然650℃下生长的纳米晶体的尺寸分布比较窄,但纳米晶体的尺寸随退火时间的延长几乎不变,在该温度改变退火时间很难改变纳米晶体的平均尺寸.在所有样品中出现了深能级缺陷,在650℃退火时间小于4h或大于16h有利 关键词： 纳米晶体 生长机理 深能级缺陷     

声纳方程的瞬态形式讨论

本文提出用瞬态信号的能谱级代替稳态信号的声强级来定义声纳参数，并以短柱声散射为例，运用数值模拟方法，验证用能谱级定义声纳参数，声纳方程是比较有效的，这为应用声纳方程处理瞬态声信号从而获得目标强度提供了一种有效可行的方法。     

原子核的振动与转动模型(Ⅲ)A～190区超形变带研究

应用推转玻尔-莫特逊哈密顿量导得了超形变带的转动谱公式,应用这一公式研究了在A～190区24个超形变带的跃迁能量和能级自旋,获得了满意的结果.     

TEM01模式激光对两能级原子的作用力研究

推导了两能级原子在稳态和小速度一阶微扰近似下的受力矢量方程，并分析表明ＴＥＭ０１模光场以原子的作用力中存在旋涡力，对在大正失谐δ〉〉Ω０〉〉Г和ｚ〈〈ｚ０＝ｋｗ＾２／λ条件下的ＴＥＭ０１模行波和驻波场中原子的受力进行了分析，对行波场，自发辐射对原子运动的影响很大，但在ｒ〈〈λ区域内原子受到横向囚禁力；对驻波场，自发辐射的影响可以忽略，考虑在ｚ方向波长范围内原子的平均受力得到的结论为：在横向，除了有     

相干驱动场的线宽对电磁感应透明的影响

考虑相干驱动场的线宽，探讨了其对双激发态原子三能级系统中的电磁感应透明现象的影响，得到结论：相干驱动场的线宽抑制了介质对弱探测光的透明。     

谐振子薛定谔方程的简单解法

物质的许多物理与化学性质都可以用线性谐振子模型解释，本文用简单的数学运算求解线性谐振子的薛定谔方程，避免了特殊函数等复杂的数学运算，得出了量子力学教材完全相同的结果。     

Gas challenge-blood oxygen level-dependent (GC-BOLD) MRI in the rat Novikoff hepatoma model

Purpose

The purpose of the study was to investigate the relationship between gas challenge-blood oxygen level-dependent (GC-BOLD) response angiogenesis and tumor size in rat Novikoff hepatoma model.

Materials and Methods

Twenty adult male Sprague-Dawley rats (weighting 301-325 g) were used for our Animal Care and Use Committee-approved experiments. N1-S1 Novikoff hepatomas were grown in 14 rats with sizes ranging from 0.42 to 2.81 cm. All experiments were performed at 3.0 T using a custom-built rodent receiver coil. A multiple gradient-echo sequence was used for R2^? measurements, first during room air (78% N₂/20% O₂) breathing and then after 10 min of carbogen (95% O₂/5% CO₂) breathing. After image acquisition, rats were euthanized, and the tumors were harvested for histological evaluation.

Results

The R2^? change between air and carbogen breathing for small hepatomas was positive; R2^? changes changed to negative values for larger hepatomas. We found a significant positive correlation between tumor R2^? change and tumor microvessel density (MVD) (r=0.798, P=.001) and a significant inverse correlation between tumor R2^? change and tumor size (r=−0.840, P<.0001).

Conclusions

GC-BOLD magnetic resonance imaging measurements are well correlated to MVD levels and tumor size in the N1-S1 Novikoff hepatoma model; GC-BOLD measurements may serve as noninvasive biomarkers for evaluating angiogenesis and disease progression and/or therapy response.     

双脉冲注入式LD模块的红外能级寿命可见区测试系统

Er3+的4I_13/2能级寿命的长短对评估Er3+掺杂材料在光通讯波段的应用十分重要。基于980 nm双脉冲注入式LD激发下的Er3+激发态吸收上转换发光,测量在不同双脉冲时间间隔下的上转换红光发光强度,再根据上转换红光的发光强度随双脉冲时间间隔的变化关系,推导出了Er3+红外4I_13/2能级寿命的拟合公式,实现了红外能级寿命的可见区测量。因此,结合兼具时间间隔可调和同步脉冲取样的双脉冲注入式LD模块和光电倍增管(R2658),就可以实现所有Er3+红外能级寿命的测量,这是一种十分经济的微秒量级荧光寿命测试系统。     

Level crossing in a two-photon Jaynes—Cummings model

In this paper,the energy spectrum of the two-photon Jaynes-Cummings model(TPJCM) is calculated exactly in the non-rotating wave approximation(non-RWA),and we study the level-crossing problem by means of fidelity.A narrow peak of the fidelity is observed at the level-crossing point,which does not appear at the avoided-crossing point.Therefore fidelity is perfectly suited for detecting the level-crossing point in the energy spectrum.