利用钛保护层在ITO电极上直接制备大面积的超薄氧化铝膜

通过磁控溅射并引入钛保护层, 利用在0.3 mol·L^-1硫酸中20 V电压下二次阳极氧化, 在氧化铟锡(ITO)导电玻璃衬底上直接制备了超薄(约140 nm, 为阳极氧化前Al厚度的一半)、大面积(约4 cm²)的多孔阳极氧化铝(AAO). 扫描电子显微镜结果表明生成的微孔与衬底垂直, 孔径和孔间距分别约为30和60 nm. 我们发现钛保护层的作用是提高了Al层的附着性并且防止ITO被腐蚀, 在此体系中钛不能被其它的金属如铬、金、银或铜代替. 紫外-可见光谱透过率结果显示在阳极氧化过程中Ti被氧化成为透明的TiO₂, 利用10-20 nm的钛保护层以及二次阳极氧化过程, 能够保证高透明度. 在ITO上直接制备的这种透明、有序的AAO纳米结构在光子学、光伏领域和纳米制备等方面具有潜在应用.     

Reduction of Concentration Quenching in a Nondoped DCM Organic Light-Emitting Diode

We obtain a nondoped red organic light-emitting diode (OLED) structure ITO/pc-PPV (-30 nm)/DCM (-30 nm)/BCP (-30nm)/Mg:Ag, where DCM refers to 4-(dicyanomethylene)-2-methyl-6-[(4-dimethylaninostyryl)-4-Hpyran]. The OLED shows pure and stable red luminescence depending on the driving voltages. The maximum luminance is 330 Cd/m^2 and the turn-on voltage is as low as-2 V. The reason why the concentration quenching of DCM could be reduced in this structure is investigated. In the preparation process, both the hole-transporting layer and the emitter layer are formed by the spin-coated method. It is believed that this method can lead to a new way to avoid the concentration quenching of red-emitting materials.     

Ray-Tracing Simulation on Filamentation of Prefocused and Freely Propagated Laser Pulses in Air

The filamentation mechanisms of prefocused and freely propagated femtosecond laser pulses axe compared using the ray-tracing method. The dynamic spatial replenishment mechanism takes place in the filaments with high electron density, which is generally formed by prefocused laser pulses. The mechanism of long-range filamentation over lOOm distance is analyzed to be the spatiotemporal moving focus.     

Fabrication of Two-Dimensional Organic Photonic Crystal Microcavity

A two-dimensional polystyrene photonic crystal microcavity is fabricated by the method ot tocused ion Oeam etching. The scanning electron microscopy and the transmittance spectrum are used to characterize the properties of the photonic crystal microcavity. The quality factor and the transmittance of the photonic crystal microcavity is more than 530 and 90%, respectively. The measured results are in agreement with the theoretical predictions.     

应用表面等离激元提高有机发光器件效率的研究进展

表面等离激元（SPP）存在于金属和介质界面,是光场和金属表面自由电子相互作用而产生的电子集体振荡行为.一方面,由于在金属纳米颗粒表面会形成局域的SPP震荡（LSP）,可以调控金属表面附近分子的发光性质,因此,很多研究者尝试在有机电致发光器件（OLED）中引入金属纳米颗粒,利用LSP改善OLED器件性能;另一方面,在传统发光器件中,由于金属表面等离激元的波矢量和自由光波的波矢量不匹配,无法辐射成自由光波,最终只能以热能的形式耗散掉.通过改变金属表面形貌,如附加光栅结构等方法,使得SPP的能量能够耦合成自由光,从而提高发光器件的外量子效率.利用SPP来提高有机发光器件的效率,已经引起广泛的关注,本文着重综述以下两个方面的工作：一是采用金属纳米颗粒的LSP提高荧光分子辐射跃迁的几率,从而提升发光器件的内量子效率;二是利用有序或无序光栅结构使得SPP与自由光的波矢匹配来提高器件的耦合出光,从而提升外量子效率.     

Lengthening the Lifetime of Long Plasma Channel in Air Generated by Femtosecond Laser Pulse

We theoretically investigate the lifetime of self-guided plasma channel in air by launching an auxiliary delayed long-pulsed laser beam following an ultrashort laser. A detailed model makes the electron-ion recombination, the attachment of electrons on neutral particles, and particularly the impact ionization and electron-detachment mechanism incorporate. The calculated results show that the temporal evolution of electron density is greatly flattened and broadened. When the auxiliary laser intensity exceeds the threshold 3.32 × 10^4 Wcm^-2, the channel lifetime is distinctly prolonged from nanosecond to microsecond, or even longer due to the electrical field enhancement. Furthermore, with the laser intensity up to 109 Wcm^-2, the impact ionization overwhelms the detachment in effect. Thus, it is an effective way to extend the channel lifetime and provides a real opportunity for applications.     

分子的飞秒强光电离

文章以一个实验者的角度，介绍了分子的飞秒强光电离的研究现状。文章从对比飞秒激光电离质谱与纳秒激光电离质谱开始，接着介绍分子在激光场作用下的可能电离机理，着重描述了几个处理分子场致电离的理论模型和实验验证，最后对飞秒激光导致的分子在激光脉冲作用后取向研究进行了简单介绍。     

超快速可调谐有机非线性光子晶体——饶毓泰基础光学二等奖介绍

光子晶体是一种新型的光子学材料,具有独特的光子带隙特性,能有效地控制光子的传输状态.可调谐光子晶体的光子带隙的位置和宽度能够随着外部参数的变化而改变,是实现集成光子器件的重要基础.文章介绍了基于有机共轭聚合物材料的非线性光子晶体的超快速可调谐特性.     

Contrast Reversal of Topography Artifacts in a Transmission SNOM

We demonstrate the contrast reversal behaviour of topography artifacts by changing the diameter of the collection diaphragm in a transmission scanning near-field optical microscopy （SNOM）. This originates from the change of the approach curves. Such contrast reversal phenomenon is used to distinguish the artifact signal from the true optical signal of the SNOM image. We also show that continuously changing the diaphragm to a proper diameter can greatly reduce topography artifacts.     

Transverse Writing of Multimode Interference Waveguides inside Silica Glass by Femtosecond Laser Pulses

Multi-mode interference waveguides are fabricated inside silica glass by transverse writing geometry with femtosecond laser pulses. The influences of several writing and reading factors on the output mode are systematically studied. The experimental results of straight waveguides are in good agreement with the simulations by the beam propagation method. By integrating a straight waveguide with a bent waveguide, a 1× 2 multi-mode splitter is formed and 2×3 lobes are observed in the output mode.