GaAs半导体中三光子吸收的非线性光电导测量

采用非线性光电导技术测量2.06μm激光激发的GaAs本征半导体三光子吸收,观察到三光子和单光子吸收的混合光电导,测得了三光子吸收系数.测量结果与理论计算符合较好.     

Growth of GaAs1−xPx/GaAs and InAsxP1−x/InP strained quantum wells for optoelectronic devices by gas-source molecular beam epitaxy

In this paper we show that pseudomorphically strained heterostructures of InAs _x P_1−x /InP may be an alternative to lattice-matched heterostructures of In_1−x Ga _x As _y P_1−y /InP for optoelectronic applications. We first studied the group-V composition control in the gas-source molecular beam epitaxy (GSMBE) of the GaAs_1-x P _x /GaAs system. Then we studied GSMBE of strained InAs _x P_1−x /InP multiple quantum wells with the ternary well layer in the composition range 0.15 <x < 0.75. Structural and optical properties were characterized by high-resolution x-ray rocking curves, transmission electron microscopy, absorption and low-temperature photoluminescence measurements. High-quality multiple-quantum-well structures were obtained even for highly strained (up to 2.5%) samples. The achievement of sharp excitonic absorptions at 1.06, 1.3 and 1.55μm at room temperature from InAs _x P_1−x /InP quantum wells suggests the possibility of long-wavelength optoelectronic applications.     

热焦距的动态测量

本文对连续（ＣＷ）Ｎｄ＾３＋：ＹＡＧ激光器的热焦距分别进行了静态和动态下的测量。结果表明在同样泵浦功率下,Ｎｄ：ＹＡＧ棒动态下的热焦距比静态下的热焦距要大。从而为精度要求比较高的谐振腔设计提供了更为精确的数据。     

He—Ne激光血管内照射与尿激酶治疗脑梗塞对比研究及微观机理初探

将６２例脑梗塞患者随机分为两组,并分别用激光血管内照射（ＩＬＩＢ）及尿激酶进行治疗,继而对两组疗效进行对比性观察、测试及评估。文末对ＩＬＩＢ的作用机理进行了分析。     

中国移动收购华润万众迈出3G与国际化第一步

10月5日,香港的移动运营商华润万众股价出现异动,在港交所的要求下,这家用户数排在各运营商第四位的运营商在股票停牌后发布公告称,公司股东华润集团、华润万众执行董事梁启雄（包括其关联方）,已经于2005年10月4日与“中国移动（香港）有限公司”签订了无约束力的三方意向性谅解备忘录,中国移动（香港）有限公司将现金出资收购华润集团和梁启雄分别持有华润万众48%和18.54%的股份,收购价为每股4.55港元.     

飞秒钛宝石激光器Kerr透镜锁模动态的特性研究

研究了Kerr透镜锁模钛宝石激光器中腔内群色散改变时脉冲的动态特性。实验研究了腔内群色散改变时输出脉冲的频谱、中心波长以及脉宽的变化规律;观测和解释了脉冲频谱的双峰结构;给出了脉冲宽度与腔内色散的具体关系式;获得了最短为14.6fs的自锁模脉冲     

High-Performing Quasi-2D Perovskite Photodetectors with Efficient Charge Transport Network Built from Vertically Orientated and Evenly Distributed 3D-Like Phases

Quasi-two-dimensional (Q-2D) perovskites are emerging as one of the most promising materials for photodetectors. However, a significant challenge to Q-2D perovskites for photodetection is their insufficient charge transport ability, which is mainly attributed to their hybrid low-dimensional n-phase structure. This study demonstrates that evenly-distributed 3D-like phases with vertical orientation throughout the film can greatly facilitate charge transport and suppress charge recombination, outperforming the prevalent phase structure with a vertical dimension gradient. Based on such a phase structure, a Q-2D Ruddlesden−Popper perovskite self-powered photodetector achieving a combination of exceptional figures-of-merit is realized, including a responsivity of 0.45 AW⁻¹, a peak specific detectivity of 2.3 × 10¹³ Jones, a 156 dB linear dynamic range, and a rise/fall time of 2.89 µs/1.93 µs. The desired phase structure is obtained by utilizing a double-hole transport layer (HTL), combining hydrophobic PTAA and hydrophilic PEDOT: PSS. Besides, the dependence of the hybrid low-dimensional phase structure is also identified on the surface energy of the buried HTL substrate. This study gives insight into the correlation between Q-2D perovskites’ phase structure and performance, providing a valuable design guide for Q-2D perovskite-based photodetectors.     

A Hetero-Layered,Mechanically Reinforced,Ultra-Lightweight Composite Polymer Electrolyte for Wide-Temperature-Range,Solid-State Sodium Batteries

The practical use of polyethylene oxide polymer electrolyte in the solid-state sodium metallic batteries (SSMBs) suffers from the retard Na⁺ diffusion at the room temperature, mechanical fragility as well as the oxidation tendency at high voltages. Herein, a hetero-layered composite polymeric electrolyte (CPE) is proposed to enable the simultaneous interfacial stability with the high voltage cathodes (till 4.2 V) and Na metallic anode. Being incorporated within the polymer matrix, the sand-milled Na₃Zr₂Si₂PO₁₂ nanofillers and nanocellulose scaffold collectively endow the thin-layer (25 µm), ultralightweight (1.65 mg cm⁻²) CPE formation with an order of magnitude enhancement of the mechanical strength (13.84 MPa) and ionic conductivity (1.62 × 10⁻⁴ S cm⁻¹) as compared to the pristine polymer electrolyte, more importantly, the improved dimension stability up to 180 °C. Upon the integration of the hetero-layered CPE with the iron hexacyanoferrate FeHCF cathode (1 mAh cm⁻²) and the Na foil, the cell model can achieve the room-temperature cycling stability (93.73% capacity retention for 200 cycles) as well as the high temperature tolerance till 80 °C, which inspires a quantum leap toward the surface-wetting-agent-free, energy-dense, wide-temperature-range SSMB prototyping.     

基于FFT的高精度FMCW雷达频率估计算法

在FMCW(调频连续波)雷达测距测速系统中,通常采用FFT(快速傅里叶变换)算法对差频信号进行频率测量。针对Rife算法在信号频率位于FFT量化频率附近时频率估计精度较低的问题,提出了一种改进的频率估计算法。该算法首先对信号作FFT并索引峰值谱线位置,然后对主瓣内幅度最大的两条谱线的系数进行线性组合,来等效实现加Hanning窗FFT,最后进行频率估计。仿真结果表明:该方法具有更高的精度,可应用于FMCW(调频连续波)雷达差频信号频率的测量,能有效地减小频率测量误差,提高距离分辨率。     

南海海边整层大气相干长度的测量与分析

大气相干长度是描述光波大气传输中湍流效应的重要参量,具有区域变化特性。海边大气相干长度的测量结果很少有报道,利用差分像运动法大气相干长度仪观测了茂名博贺海边的整层大气相干长度,获得了海边大气相干长度的全天数据。数据分析表明,海边整层大气相干长度日变化明显,夜晚起伏无规则,上半夜平均天文视宁度好于下半夜,白天最差;与陆地数据比较得知,海边整层大气相干长度日变化不如陆地上的剧烈,海边日变化成近"V"型,陆地上的为近"U"型;通过分析比较,提出了一些启发性的见解。