行波光电二极管级联阵列输出功率合成研究

针对未来光载无线通信所需的高功率、大带宽的光电探测器,提出了一种行波光电二极管级联阵列功率合成电路.先将行波光电二极管级联,再按照阵列式结构将多组级联的光电二极管组合起来,实现射频功率合成,以获得高功率、大带宽的射频信号.采用EDA工具,对该光电转换射频功率合成电路进行仿真模拟.仿真结果表明,该功率合成电路可以有效地将各光电二极管的射频输出信号进行功率合成,功率合成后的信号带宽显著增加,仿真结果与理论分析完全一致.此外,电路分析表明,增加该功率合成电路中的高阻微带线的特性阻抗可以有效提高其输出射频信号的带宽.     

吡啶取代蒽衍生物电荷传输性质的理论研究

采用DFT,HF,CIS和TDDFT等方法对5个吡啶取代蒽衍生物的电子结构、光谱及电荷注入传输性能进行了计算与研究.结果表明,5种化合物的结构变化发生在相邻基团之间的二面角,电子光谱变化微小,最大发射波长约450nm.通过调节吡啶或苯的取代位置,可改变前线分子轨道能级、电离能、电子亲和势和重组能的大小,改善化合物的电荷注入传输性能.5种化合物中,DPyPA-MO的空穴和电子迁移速率较为突出,而DPyPA-OM具有最佳的电荷注入传输性能,有望成为电荷平衡性优良的蓝光材料应用于OLED.     

高效液相色谱/二极管阵列检测器同时测定辣椒及其制品中11种脂溶性着色剂

建立了一种简单、快速同时测定辣椒及其制品中苏丹橙G、甲基黄、对位红、柑桔红2号、苏丹红G、苏丹Ⅰ、苏丹Ⅱ、苏丹Ⅲ、苏丹红7B、苏丹红B、苏丹Ⅳ11种脂溶性着色剂的分析方法。样品经乙酸乙酯提取后采用凝胶渗透色谱净化,用配有二极管阵列检测器的高效液相色谱法测定,外标法定量。结果表明,11种着色剂在20~1 000μg/L范围呈良好线性,线性系数均大于0.998。在10、20、40μg/kg 3个加标水平下的平均回收率为75.8%~90.8%,相对标准偏差为3.0%~7.8%,11种着色剂的定量下限为10μg/kg。该方法稳定、可靠,适用于辣椒和辣椒酱中11种着色剂的测定。     

Gallium Nitride Room Temperature α Particle Detectors

Gallium Nitride （GaN） room temperature α particle detectors are fabricated and characterized, whose device structure is Schottky diode. The current-voltage （I- V） measurements reveal that the reverse breakdown voltage of the detectors is more than 200 V owing to the consummate fabrication processes, and that the Schottky barrier and ideal factor of the detectors are 0.64 eV and 1.02, respectively, calculated from the thermionic transmission model. ^241Am α particles pulse height spectra from the GaN detectors biased at -8 V is obviously one Gauss peak located at channel 44 with the full width at half maximum （FWHM） of 15.87 in channel. One of the main reasons for the relatively wider FWHM is that the air between the detectors and isotope could widen the spectrum.     

肖特基结的制备与势垒测量

采用磁控溅射方法在Nb07％-SrTiO3基片上制作Au薄膜接触,并在氧气气氛下750℃退火30 min,在室温环境下测量电流电压和电容电压等特性曲线,观测整流特性,根据相应实验数据采用饱和电流法、电容C-2与反偏电压V成线性关系计算肖特基势垒的大小.     

Influence of spacer layer thickness on the current-voltage characteristics of pseudomorphic AlAs/In0.53Ga0.47As/InAs resonant tunnelling diodes

This paper investigates the dependence of current voltage characteristics of AlAs/In0.53Ga0.47As/InAs resonant tunnelling diodes （RTDs） on spacer layer thickness. It finds that the peak and the valley current density J in the negative differential resistance （NDR） region depends strongly on the thickness of the spacer layer. The measured peak to valley current ratio of RTDs studied here is shown to improve while the current density through RTDs decreases with increasing spacer layer thickness below a critical value.     

Judd--Ofelt analysis of spectra and experimental evaluation of laser performance of Tm3+ doped Lu2SiO5 crystal

This paper reports that the Tm^3＋：Lu2SiO5 （Tm：LSO） crystal is grown by Czochralski technique. The roomtemperature absorption spectra of Tm：LSO crystal are measured on a b-cut sample with 4 at.% thulium. According to the obtained Judd-Ofelt intensity parameters Ω2=9.3155×10^-20 cm^2, Ω4=8.4103×10^-20 cm^2, Ω6=1.5908×10^-20 cm^2, the fluorescence lifetime is calculated to be 2.03 ms for ^3F4 → ^3H6 transition, and the integrated emission cross section is 5.81×10^-18 cm^2. Room-temperature laser action near 2μm under diode pumping is experimentally evaluated in Tm：LSO. An optical-optical conversion efficiency of 9.1% and a slope efficiency of 16.2% are obtained with continuouswave maximum output power of 0.67 W. The emission wavelengths of Tm：LSO laser are centred around 2.06μm with spectral bandwidth of -13.6 nm.     

p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定，推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下，二极管的时间常数由材料本身来决定，与外加电流频率无关.高频情况下，时间常数则与半导体材料性质无关，只由外加交流电的频率来决定.     

Edge-pumped passively Q-switched thin Nd:YAG slab lasers

We report a high-power thin Nd：YAG slab laser with slab dimension of 1 × 10 ×60 （mm） partially edgepumped by diode laser arrays. Passive Q-switching is achieved with a Cr^4＋ ：YAG microchip adopted as the saturable absorber mirror. The pulse duration is around 10 ns while the pulse repetition rate is higher than 10 kHz. The average output power of 70 W is obtained with a slope efficiency of 36%. The diffraction limited beam quality in the thickness direction is obtained by controlling the pump beam diameter inside the slab. The laser head is very compact with size of only 60 × 74×150 （mm）.     

用于闪光照相的1MV Rod-Pinch二极管辐射特性

Rod-Pinch二极管(RPD)在小尺度闪光照相方面具有良好的应用前景.根据理论方面的研究结果以及实验室具备的驱动源装置水平,设计了相应结构的RPD,并在1MV工作电压下开展了较为详细的性能实验研究.最终在二极管轴向(0.方向)lm处得到的x光剂量为1.21rad-1.45rad.对于阳极直径为lmm的二极管,其X光焦斑直径仅为0.8mm-1.1mm.X光信号的脉宽为18.1ns-27.5ns.研究表明RPD将是一种用于小尺度闪光照相的理想的X光源.