数字图像处理在塞曼效应实验中的应用

利用计算机对塞曼效应实验进行了数字图像处理,使实验精度有很大提高,实验时间缩短,该方法对拓宽学生知识面,开发计算机的应用起到了一定作用,值得在其它实验中推广。     

单块偏振片反射式向列相液晶显示器的理论设计与实验制造研究

反射式液晶显示器(RLCDs)具有亮度高、无视差等优点,并且结构简单,适合于现行的制造工艺和驱动方式.本文利用我们提出的参数空间法(偏振片角度、扭曲角及双折射率的函数)研究了适用于反射式液晶显示器,这种研究表明所有的反射式液晶显示模式都可以在这个参数空间里得以表述,如扭曲向列型的电控双折射模式(TN-ECB),混合场效应模式(HFE),混合向列型模式(MTN),以及自补偿向列型模式(SCTN).在此基础上我们提出几种新的反射模式,如反射向列型及反射超扭曲向列型(通过搜索参数空间得到),二者均适用于直视型和投影型显示方式.我们已制成反射向列型及反射超扭曲向列型样品,实验结果和理论设计符合一致.     

Measurement of the optical transmission modes and losses of the poled guest–host polymer NAEC/PEK-c planar waveguides

The polyetherketone (PEK-c) guest–host polymer planar waveguides doped with (4′-nitro)-3-azo-9-ethyl-carbazole (NAEC) were prepared. The waveguide films were poled by corona-onset poling at elevated temperature (COPET), and the corona poling setup includes a grid voltage making the surface-charge distribution uniform. By using the prism-in coupling method, the dark-line spectrum given by the reflected intensity versus the angle of incidence have been obtained, and the optical transmission losses of mth modes have been measured for the poled polymer waveguides at λ=632.8 nm. The measurement result showed that the optical loss of the fundamental mode is less than 0.7 dB cm⁻¹ for the TE polarization.     

有机分子束外延技术与研究进展

本介绍了超高真空分子束外延生长有机薄膜的技术及基研究进展,讨论了外延材料的纯化过程和杂质对外延薄膜的影响;从理论和实验观点评论了薄膜的生长性质和膜的有序结构。超高真空有机分子束外延技术是一种多用途的高技术,可以生长有机、无机、有机／无机混和的薄膜结构。这种薄膜结构是示来光学和电子器件有希望应用的新一类工程材料。     

Optical fiber acoustic sensing multiplexing system based on TDM/SFDM

We propose a system of time-division multiplexing(TDM) and spatial frequency-division multiplexing(SFDM). Extrinsic Fabry–Perot interferometric sensors are applied to detect weak acoustic signals. The broadband source is employed, the light from it is modulated by a pulse signal sequence and is efficiently amplified by semiconductor optical amplifiers. Experimental results show that the equivalent noise pressure spectrum level is-97.2 d B re 1 rad/√Hz below 1250 Hz, and the cross talk between two sensors in one TDM channel is-32.7 d B with a cavity length difference of 60 μm. The number of sensors in this multiplexing system can theoretically reach 160.     

Distributed Bragg reflector laser(1.8 μm) with 10 nm wavelength tuning range

We report a 1.8 μm two-section distributed Bragg reflector laser using butt-jointed In Ga As P bulk material as the waveguide core layer. The threshold current is 17 m A and the output power is 8 m W on average. The threshold current, output power, and emitting wavelength dependences on temperature are measured. The obtained wavelength tuning range is 10 nm. This device has potential applications in simultaneous multiple-gas detection.     

砷化镓光阴极直流高压注入器研究进展

主要介绍自由电子激光相干强太赫兹源(FEL-THz)装置上的砷化镓光阴极直流高压注入器的研究进展,并讨论其驱动未来高重复频率短波长自由电子激光器的差距。通过综合砷化镓阴极寿命的三大影响因素,提出了其工作寿命的定性物理模型;通过该模型对阴极和注入器进行优化,在直流高压电子枪上得到了5mA,32min的连续稳定输出;测量了电子束在4.8mA下归一化发射度约为4.0πmm·mrad,阴极热发射度约为0.6πmm·mrad,电子束本征横向能量约为92meV,250keV电子束在距离阴极90.6cm处纵向均方根长度约为11.5ps。这一束流状态已经基本满足FEL-THz需求。     

Spontaneous Ga incorporation in ZnO nanowires epitaxially grown on GaN substrate

Surface‐diffusion‐induced spontaneous Ga incorporation process is demonstrated in ZnO nanowires grown on GaN substrate. Crucially, contrasting distributions of Ga atoms in axial and radial directions are experimentally observed. Ga atoms uniformly distribute along the ～10 μm long ZnO nanowire and show a rapidly gradient distribution in the radial direction, which is attributed substantially to the difference between surface and volume diffusion. The understanding on the incorporation process can potentially modulate doping and properties in semiconductor nanomaterials.