1064nm RCE探测器光电响应特性分析

对1064nm谐振腔增强型（RCE）光电探测器(PD)的光电响应特性进行了分析研究．利用MBE生长技术得到有源区分别为量子阱和量子点的1064nm RCE探测器的外延片,并对制作的探测器进行了各种光电特性测试．结果表明量子阱结构的RCE探测器量子效率峰值达到57%,谱线半宽6～7nm,峰值波长1059nm;而量子点结构的RCE探测器量子效率峰值达到30%,谱线半宽5nm,峰值波长1056nm．通过分析量子效率和吸收系数之间的关系,对两种结构器件的吸收进行了比较,发现虽然量子点探测器的吸收小,但通过合理设计共振腔等方法也可以达到较高的量子效率．两种结构的器件都有很好的Ｉ-Ｖ特性．     

从吐哈油田HFC网的建设看有线电视的发展趋势

1　引言1993年 9月美国政府提出“信息高速公路计划” ,掀起了全球开发高速通信网的热潮 ,基于电路交换的数字数据网 (ＤＤＮ)、窄带综合业务数字网 (ＩＳＤＮ) ;基于分组交换的光纤分布数据接口网 (ＦＤＤＩ)、ＦＲ帧中继网以及ＡＴＭ等技术的出现 ,使通信网能在干线或局域网中实现高速大容量的信息传递。然而这些网络大多为共享型 ,传输量有限 ,易形成“瓶颈”现象 ,因此目前制约通信的主要障碍是接入网技术 ,即“最后 1ｋｍ”问题。ＨＦＣ有线电视网以其频带宽、容量大、低成本、双向性等优势 ,并兼顾现有的模拟信息和数字信息 ,是目前接…     

Material Growth and Device Fabrication of GaAs Based 1.3μm GaInNAs Quantum Well Laser Diodes

Material growth and device fabrication of the first 1.3μm quantum well (QW) edge emitting laser diodes in China are reported.Through the optimization of the molecular beam epitaxy (MBE) growth conditions and the tuning of the indium and nitrogen composition of the GaInNAs QWs,the emission wavelengths of the QWs can be tuned to 1.3μm.Ridge geometry waveguide laser diodes are fabricated.The lasing wavelength is 1.3μm under continuous current injection at room temperature with threshold current of 1kA/cm2 for the laser diode structures with the cleaved facet mirrors.The output light power over 30mW is obtained.     

紫外激光无损检测潜在指印技术研究

潜在指印的显现是物证检验技术中的关键问题之一,而紫外(UV)照相技术是显现潜在指印等隐性痕迹物证的重要技术手段。采用266 nm紫外固体激光器为激发光源,利用人体指印固有物质成分对紫外光具有特殊的吸收、反射、散射及荧光特性,减弱或消除指印背景上的图案和其他细节干扰,增加指印纹线与背景的亮度反差,显出或增强潜在指印。通过紫外反射照相及紫外固有荧光照相技术,分别实现了对彩色杂志纸张、玻璃、电话背面、木纹桌面油漆面4种非渗透性物证检材及牛皮纸信封、便签纸2种渗透性物证检材表面遗留的新鲜及陈旧潜在指印的无损检测显现,并具有鉴定价值。     

用开口波导反射法测量材料电磁特性的新技术

本文提出用开口波导反射法同时测量高损耗材料电磁参数εｒ,μｒ的新技术。用开口波导作传感器,测量样品加载时的复反射系数,并与以εｒ,εｒ为变量的理论计算值相比较,运用优化技术求得待测材料的电磁参数。     

激光对望远系统损伤的研究

本文对激光光束通过望远系统后光束的变化进行了分析，并对６倍望远镜进行了激光损伤和破坏的实验研究，实验结果表明，激光对望远系统的损伤破坏主要是热效应所致，损伤破坏的情况与激光的能量，波长，脉冲宽度和望远系统的结构有关。     

蛋白质与原卟啉Ⅸ及复合物发光机理探讨

对原卟啉Ⅸ（ＰｒｏｔｏｐｏｒｐｈｙｒｉｎⅨ）与蛋白质结合物的吸收、荧光的激发、发射光谱等的研究，表明了在光作用下，其可见区发光（λｍａｘ６３５ｎｍ左右）与卟啉有关，而紫外区发光（λｍａｘ４２２ｎｍ左右）与蛋白质的色氨酸残基有关，其光谱特性与临床诊断选择的癌固有荧光特征峰基本相符。该研究结果为探讨癌的发光机理积累了有益资料．     

The Research on 220GHz Multicarrier High-Speed Communication System

This paper presents our investigation into a 220 GHz multicarrier highspeed communication system based on solid state transceivers.The proposed system has eased the demand of high sampling rate analog-to-digital converter(ADC)by providing several signal carriers in microwave band and converting them to 220 GHz channel.The system consists of a set of 220 GHz solid-state transceiver with 2 signal carriers,two basebands for 4 GSPS ADCs.It has achieved 12.8 Gbps rate real-time signal transmission using 16QAM modulation over a distance of 20 m without any other auxiliary equipment or test instruments.The baseband algorithm overcomes the problem of frequency difference generates by non-coherent structure,which guarantees the feasibility of long-distance transmission application.Most importantly,the proposed system has already carried out multi-channel 8K video parallel transmission through switch equipment,which shows the multicarrier high-speed communication system in submillimeter wave has great application prospects.To the best of the authors’knowledge,this is the first all-solid-state electronics multicarrier communication system in submillimeter and terahertz band.     

High-power Mode Converter of Overmoded Bent Circular Waveguide

Based on the mode coupling theory, a TE₀₁—TM₁₁ mode converter was designed and optimal results were obtained. In this paper, bandwidth of mode converter with axis exponential structure is the largest, and mode converter with axis sinusoidal structure is the most compact in the case of the center frequency is 28GHz and the waveguide radius is 16mm. If the bending angle between input port and output port of mode converter was demanded for 90°, mode converter with axis parabola structure had the characteristics of compact structure, higher mode purity and larger relative bandwidth. Meanwhile, we found that the converter could be also used as TE₁₁ mode transition with transmission efficiency above 99%. But due to bending angle of this structure was restricted, its center frequency and waveguide radius had the obvious corresponding relation.     

Scaling and technological limitations of 1/f noise and oscillator phase noise in SiGe HBTs

This paper examines the impact of SiGe HBT scaling on 1/f noise and phase noise of oscillators and frequency synthesizers. The increase of transistor speed with scaling is shown to significantly increase the sensitivity of oscillation frequency to 1/f noise and, thus, degrade close-in phase noise, but decrease the sensitivity of oscillation frequency to base current shot noise and base resistance thermal noises. The results show that corner offset frequency defined by the intersect of the 1/f³ and 1/f² phase noise has little to do with the traditional 1/f corner frequency. The relative importance of individual noise sources in determining phase noise is examined as a function of technology scaling, device sizing, and oscillation frequency. The collector current shot noise and base resistance noise are shown to set the fundamental limits of phase noise reduction. A methodology to identify the maximum tolerable 1/f K factor is established and demonstrated for the HBTs used