Saturation of absorption by lead sulfide nanoparticles in the main absorption band region

The spectral dependence of the degree of bleaching of glasses with PbS nanoparticles (average radius from 3 to 4 nm) has been studied in the main absorption band region. It has been established that the level of residual absorption in the bleached state decreases from 0.70 to 0.02 as we go from the high-frequency edge of the main absorption band for the lead sulfide nanoparticles toward the low-frequency edge, and reflects the spectral features of absorption by charge carriers in excited states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 195–199, March–April, 2006.     

萘酞菁锌化合物的光限幅特性研究

应用倍频Ｎｄ：ＹＡＧ脉冲激光,在波长为５３２ｎｍ,脉冲宽度分别为８ｎｓ和２３ｐｓ的条件下,研究了四溴 ２,３ 萘酞菁锌（Ⅱ）（ｔｅｔｒａｂｒｏｍｏ ２,３ ｎａｐｈｔｈａｌｏｃｙａｎｉｎｅＺｉｎｅ（Ⅱ））化合物的光限幅特性,其光限幅特性优于富勒烯。研究结果表明,激发态吸收是主要的光限幅机理。     

A Quick Numerical Method for Analyzing Nonlinear Effects of Excited State Absorption

１　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗｈｅｎｕｌｔｒａｓｈｏｒｔ,ｈｉｇｈｉｎｔｅｎｓｉｔｙｌａｓｅｒｐｕｌｓｅｓｉｎｔｅｒａｃｔｗｉｔｈａｍｕｌｔｉｅｎｅｒｇｙｌｅｖｅｌｍｏｌｅｃｕｌａｒｓｙｓｔｅｍ,ｔｈｅｂｕｉｌｄｕｐｏｆｐｏｐｕｌａｔｉｏｎｉｎｅｘｃｉｔｅｄｓｔａｔｅｓｗｉｌｌｌｅａｄｓｔｏａｒｅｄｕｃｔｉｏｎｏｒａｎｉｎｃｒｅａｓｅｏｆｔｈｅａｂｓｏｒｐｔｉｏｎｃｏｅｆｆｉｃｉｅｎｔ,ｗｈｉｃｈａｒｅｒｅｆｅｒｒｅｄｔｏａｓｓａｔｕｒａｂｌｅａｂｓｏｒｐｔｉｏｎ（ＳＡ,ｉ．ｅ．,ａｎ…     

A Quick Numerical Method for Analyzing Nonlinear Effects of Excited State Absorption

A semi-analytical difference method for analyzing nonlinear effects of excited state optical absorption is presented. In comparison with Hughes' method and traditional difference method, the advantages of the semi-analytical difference method are speed-up in computation time, high accuracy and good stabilization.     

PPV衍生物的激发态动力学特性研究

利用共振飞秒光学克尔效应研究了C10－PPV溶液的非线性光学响应。实验结果表明,在共振激发条件下,C10－PPV挑学克尔效应信号表现为快速上升和随后的驰豫过程,其驰豫过程由两部分组成,一个200fs的快过程和一个400ps的慢过程。通过比较C10－PPV和掺杂C60后的C10－PPV荧光光谱,400ps的慢过程可归属为聚合物链内单重态激子在不同共轭段间的迁移过程。     

有机染料HEASPS在不同波长时的激发态吸收和双光子吸收性质研究

提出了有机染料反式 4 [4′ (N 羟乙基 N 乙基胺基 )苯乙烯基 ] N 甲基吡啶对甲苯磺酸盐 (简称HEASPS)非线性吸收的三态模型。认为在较短波长 (<1 0 0 0nm)时 ,双光子吸收和激发态吸收同时存在。成功地解释了该染料双光子吸收峰相对线性吸收峰的两倍的明显蓝移 ,以及最高上转换效率波长相对最强吸收波长的明显红移。提出了一种新的计算方法 ,利用不同波长的非线性透过率和不同波长的上转换效率 ,求出了该染料的双光子吸收截面和激发态吸收系数。     

线阵CCD用于长距离衍射准直测量

本文介绍了在半导体激光光纤与位相板相结合的准直情况下,利用线阵ＣＣＤ探测器测量大型工件形位误差遇到的光强变化而引起测量误差的问题,并对用线阵ＣＣＤ进行衍射信号测量的原理和特点作了分析。根据ＣＣＤ的工作原理和特性,提出了利用自动控制ＣＣＤ积分时间的方法,使ＣＣＤ输出的信号峰值保持恒定,提高了系统的测量精度。     

Two-photon absorption by Nd3+ impurity ions in YAG and YLF crystals at 1.06 μm

A detailed theoretical analysis of the two-photon absorption spectra for YAG: Nd³⁺ and YLF: Nd³⁺ crystals was carried out in the 1.06 μm region with calculations of both the relative intensities between individual Stark sublevels of the⁴I_9/2→⁴G_7/2 transition of an Nd³⁺ ion and the integral two-photon absorption crosssections. The results of calculations agree well with experimental data. Reasons why the explanation of the experimental data given in [3] is very unsatisfactory and largely doubtful in itself are indicated. In conclusion, a relatively simple experiment is suggested that could give an unambiguous answer to some questions of the theoretical analysis performed. B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 2, pp. 184–189, March–April, 1997.     

Transient excited singlet state absorption in Rhodamine 6G

Transient excited singlet state absorption (ESSA) has been studied in Rhodamine 6G in ethanol using a nitrogen laser and nitrogen laser-pumped dye laser. Broad absorption with several submaxima and possible shoulders, which represent the vibrational structure, has been observed in Rhodamine 6G in the region, 4175–4640 Å. The position of the lowest vibrational level of the first excited singlet stateS ₁ has been determined from the crossing point of the long and short wavelength spectral wings of absorption and fluorescence respectively. The energy level scheme of the molecule has been obtained with the help of the absorption and fluorescence spectra recorded. The observed structure in ESSA has been tentatively interpreted to be due to transitions from the different vibrational levels ofS ₁ to one or more vibrational levels of the upper singlet electronic stateS ₄.     

含Cr离子饱和吸收体被动调Q解析解

讨论了慢恢复饱和吸收体的被动调Ｑ过程，在合理简化被动调Ｑ速率方程组的基础上，得到了能反映激发态吸收效应的慢恢复饱和吸收体被动调Ｑ的判据，以及调Ｑ脉冲的峰值功率，脉冲能量，脉冲宽度和能量利用率等调Ｑ重要参量的解析表达式，结果具有一定的普遍性，有助于这类被动调Ｑ激光器的优化设计。     

LaF3晶体中Ho3+离子的上转换发光机理研究

首次系统研究了在连续可调谐红色染料激光激发下,掺杂Ho3+离子的氟化镧LaF3晶体的上转换发光特性.根据对样品的激发、发射光谱和发光的上升、衰减等动力学过程的分析,仔细地研究了Ho3+离子上转换发光的机理,并建立了不同上转换发光过程的动力学模型.以这些模型为基础,对实验结果进行了分析和验证.     

Fluorescence quenching in dyes under an optically thin approximation

Kinetic analysis of the energy level scheme of a dye molecule yields expression for the fluorescence quantum yield. The quantum yield is dependent on molecular parameters and laser pulse characteristics. Calculations show quenching of fluorescence quantum yield due to excited state absorption. Earlier studies on quenching of fluorescence have been discussed quantitatively under an optically thin approximation.     

C_（60）／PMMA的单重态激发态吸收光限幅研究

研究了Ｃ６０／ＰＭＭＡ对波长５３２ｎｍ，脉冲宽度为２１ｐｓ的脉冲激光的限幅特性，并应用三能级模型进行了理论模拟。结果表明光限幅起源于单重态激发态吸收     

Cr^4＋：YAG被动调Q激光器输出特性的解析分析

在考虑Cr^4＋：YAG晶体激发态吸收的情况下，给出了Cr^4＋：YAG被动调Q的Nd：YAG激光器的速率方程组，从该速率方程组出发推导出了Nd：YAG被动调Q激光器的输出能量、脉冲宽度和效率的解析解，并分析了各参量之间的相互耦合关系。结果表明，在考虑了Cr^4＋：YAG晶体激发态吸收的情况下，理论上能够正确地反应出Cr^4＋：YAG晶体的吸收特性，对设计和优化Cr^4＋：YAG被动调Q激光器有一定的指导意义。     

Cr~(4+): YAG被动调Q与激发态吸收饱和

运用速率方程计算了Ｃｒ４＋ＹＡＧ晶体的基态吸收、激发态吸收与入射脉冲的能量密度和强度的关系。在测量晶体透过率的实验中，发现Ｃｒ４＋ＹＡＧ晶体的激发态吸收趋于饱和。理论计算与实验数据拟合给出了包括基态吸收截面，激发态吸收截面和寿命等参数。在用Ｃｒ４＋ＹＡＧ对脉冲式ＮｄＹＡＧ激光器被动调Ｑ的实验中，得到脉宽５ｎｓ、能量９０ｍＪ的激光脉冲，并且发现这种调Ｑ与Ｃｒ４＋ＹＡＧ的激发态吸收饱和直接相关。     

新型金属团簇化合物的光限幅特性研究

应用倍频 Nd:YAG脉冲激光 ,在波长为 5 32 nm、脉冲宽度为 8ns的条件下 ,研究了金属团簇化合物WOS3Cu3I(2 - Me Py) 3的光限幅特性。其光限福特性优于富勒烯。Z- Scan研究结果表明 :该团簇具有自聚焦特性 ,其光限幅起源于激发态吸收     

Optical Signal Inversion Phenomenon for 1.5 μm Derived from the Negative Nonlinear Absorption Effect in an Erbium Nitrate Solution

The modulation characteristics of the negative nonlinear absorption effect were investigated in an erbium nitrate solution using a 1510 nm laser diode. The reversed-phase waveform was obtained in the transmitted laser for a sample length of 3.0 mm. With decrease in the modulation degree, the reversed-phase waveforms were observed at modulation degrees smaller than 72%. With increase in the modulation frequency, the transmitted waveforms were asymmetrical. The optical signal inversion phenomenon for 1.5μm can be explained by considering an excited state absorption in which energy transfer occurs in a system with high concentrations of the Er3+ ion.     

Er3+,Yb3+共掺杂SrTiO3超细粉末的可见上转换发光

钛酸锶(SrTiO₃)具有高介电常数、良好的绝缘性质、优良的物理化学稳定性和在可见光范围内的优异的透明度等优点,是一种重要的无机功能材料。近年来,Al³⁺,Ga³⁺等离子共掺杂的SrTiO₃:Pr³⁺做为一种优异的红色场发射显示(FED)荧光粉引起了人们的兴趣。另外,SrTiO₃具有相对较小的声子频率,因而它可以作为一种有利于上转换发光的基质材料。以NaCl为助熔剂制备了Er³⁺,Yb³⁺共掺杂的SrTiO₃超细粉末。在980nm激发下,样品发出很强的来自于Er³⁺离子的²H_11/2→⁴I_15/2,⁴S_3/2→⁴I_15/2(绿光)和⁴F_9/2→⁴I_15/2(红光)跃迁的上转换发光。Yb³⁺离子的共掺杂对Er³⁺离子的上转换发光起明显的增强作用。研究了上转换发光强度与稀土离子浓度以及激发光强度之间的依赖关系,表明在Er³⁺单掺杂和Er³⁺,Yb³⁺共掺杂的样品中,绿光和红光都是被双光子激发过程激发的。还对上转换发光的机理做了初步分析。