Yb3+离子掺杂浓度对Yb∶YAG晶体发光及荧光寿命的影响

研究了不同掺杂浓度Yb∶YAG晶体的发光特性和荧光寿命.Yb3+在YAG晶体中的掺杂浓度分别为5at%、10at%、20at%、30at%.Yb3+离子掺杂浓度越高，Yb∶YAG晶体的吸收系数越大.采用940 nm波长的LD泵浦源和TRIA X550荧光谱仪，对这一系列掺有不同浓度Yb3+的Yb∶YAG晶体进行了荧光光谱的测定.结果表明:在1030 nm主发光波段的荧光强度以10at%Yb∶YAG的为最强.同时发现它在450 nm-680 nm波段有明显的可见发光，其强度随Yb3+掺杂浓度的增加而迅速地增强.Yb∶YAG晶体的荧光寿命存在浓度猝灭现象，对猝灭机制进行了分析研究，指出浓度猝灭的主要原因是合作发光和痕量稀土离子的上转换发光.     

Propagations of Fresnel diffraction accelerating beam in Schrödinger equation with nonlocal nonlinearity

Accelerating beams have been the subject of extensive research in the last few decades because of their self-acceleration and diffraction-free propagation over several Rayleigh lengths. Here, we investigate the propagation dynamics of a Fresnel diffraction beam using the nonlocal nonlinear Schrödinger equation (NNLSE). When a nonlocal nonlinearity is introduced into the linear Schrödinger equation without invoking an external potential, the evolution behaviors of incident Fresnel diffraction beams are modulated regularly, and certain novel phenomena are observed. We show through numerical calculations, under varying degrees of nonlocality, that nonlocality significantly affects the evolution of Fresnel diffraction beams. Further, we briefly discuss the two-dimensional case as the equivalent of the product of two one-dimensional cases. At a critical point, the Airy-like intensity profile oscillates between the first and third quadrants, and the process repeats during propagation to yield an unusual oscillation. Our results are expected to contribute to the understanding of NNLSE and nonlinear optics.     

被动光学限幅器的机制与研究进展

被动光学限幅器是利用介质的非线性光学性质实现对光的强度进行控制的器件，它在科研，军事和民用方面都具有广泛的应用，文章讨论了被动光学限幅器的反饱和吸收，双光子吸收，自由载流子吸收，非线性折射，光致散射和光折变机制，每种机制在光限幅器应用中的有效性及局限性，介绍了国内外研究状况及自己的工作；指出了今后被动光学限幅器研究的发展方向。     

大学物理与中学物理在教学内容与教学方法上的衔接

从教学内容与教学方法两个方面,对如何加强大学物理与中学物理之间的衔接进行了分析和探讨.     

p-HPcCo和p-HPcZn的非线性光学性质研究

采用皮秒Z-扫描技术研究了两种不同中心金属取代的酞菁配合物2,9,16,23-四-(对羧基苯氧基)酞菁钴(p-HPcCo)和2,9,16,23-四-(对羧基苯氧基)酞菁锌(p-HPcZn)的非线性光学性质,并从离域电子共轭结构理论和共振、非共振增强理论进行了分析.结果表明:吸电子能力强的金属离子Zn2+取代的p-HPcZn的吸收带相对于Co2+取代的p-HPcCo略有红移;两种样品均具有正的三阶非线性极化率,共振增强使得p-HPcZn和p-HPcCo的三阶非线性极化率在532nm条件下比1064nm条件下增强了近两个量级,中心金属离子强的吸电子能力使得p-HPcZn的三阶非线性极化率大于p-HPcCo,并在532nm激发时,χ(3)具有最大值1.76×10-10esu.     

几种新型金属配合物热致三阶非线性光学特性

利用连续激光Z-扫描方法研究了过渡金属Ni、Cu、Pd的新型有机配合物的热致三阶非线性光学特性。结果表明：在488nm和632．8nm波长连续激光激发下,这几种配合物的光学非线性折射主要来源于热效应。并由实验曲线计算了它们的热光系数dn／dT及热致非线性折射率n2。通过比较,发现热致非线性折射率与配合物分子结构、激发波长及在该波长下的线性吸收强弱有关。金属中心原子的原子序数越大,热光系数和折射率也相应的越大。在488nm波长激光激发下的dn／dT和n2大于该配合物在632．8nm波长激发下的dn／dT和n2,在同一波长下,化合物溶液在该波长下的吸收越强,其dn／dT和n2值也越大。     

两种聚对苯乙炔类衍生物的线性与非线性光学性质

采用吸收光谱、荧光光谱和皮秒Z-扫描等实验方法研究了侧链长度的不同对聚[2-甲氧基-5-(2′-乙基-己氧基)]对苯乙炔(MEH-PPV)和聚(2,5-二辛氧基)对苯乙炔(DO-PPV)两种聚对苯乙炔(PPV)衍生物光学性质的影响,并用π-电子共轭结构理论和共振、非共振增强理论进行了分析。结果表明,侧链较长的MEH-PPV的吸收峰和荧光发射峰比DO-PPV相应的吸收和荧光峰均有所红移;侧链结构及共振增强使得MEH-PPV的三阶非线性极化率比DO-PPV增强了近两个量级,并在532 nm激发时,χ(3)具有最大值9.30×10-10esu。     

一种新的镍单核配合物的连续光限幅效应研究

用Z-扫描技术研究了一种新的镍单核配合物(N,N′-二[2(1-乙酰基丙烯)]乙二胺合镍)的光限幅特性。测量了在不同波长下样品的出射功率与入射功率的关系。实验结果表明该配合物是一种有较大潜在应用价值的新型光限幅材料。     

Large Third-Order Optical Nonlinearity of Cadmium Sulphide Nanoparticles Embedded in Polymer Thin Films

A simple method for synthesis of well dispersed cadmium sulphide nanoparticles embedded in a polyethylene glycol matrix （PEG 400） in thin film form is presented. The large blue shift of the band gap energy of the CdS nanoparticles compared to the bulk semiconductors is observed via UV-vis absorption spectra. Photoluminescence spectra of CdS nanocomposite films show that the emission peaks shift towards the longer wavelength with the increase of annealing temperature. Transmission electron microscopic images as well as Raman scattering studies confirm the CdS nanometer size particle formation within the polymer matrix. The particle size is about 8 nm. Selected area electron diffraction （SAED） shows the cubic zinc blende polycrystalline rings. Third-order optical nonlinearity of the CdS nanopartieles embedded in polymer thin films is studied with the Z-scan technique under 1064 nm excitation. The results show that the CdS nanocomposite film exhibits negative nonlinear refraction index and positive absorption coefficient. The film shows large optical nonlinearity, and the magnitude of the third-order nonlinear susceptibility of the film is calculated to be 1.73 × 10^-9 esu. The corresponding mechanism is discussed.     

CdSe量子点的线性和非线性光学特性

主要从实验和理论两个方面,探讨了强受限尺寸区域内不同尺寸对CdSe量子点线性和非线性光学性质的影响.用吸收光谱研究了量子点尺寸与吸收峰之间的关系,用皮秒Z扫描技术研究了共振和非共振情况下(激发光波长分别为532和1064nm),尺寸与三阶非线性极化率之间的关系.基于电子能量状态理论和局域场增强理论对量子点进行分析,得到了CdSe不同尺寸的三阶非线性效应,研究了尺寸对量子点非线性光学性质的影响.结果表明,由激发态粒子数布局改变和纳米颗粒增大引起的非线性共振增强效应相当,二者共同作用使得三阶极化率增强20倍左右,且用532nm的共振频率激发4.3nm CdSe量子点时,χ⁽³⁾具有最大值2.0×10^-11esu. 关键词： CdSe量子点 三阶非线性 Z扫描')" href="#">Z扫描 量子限域效应