半导体异质结及其在光电子学中的应用

瑞典皇家科学院2000年10月10日宣布,将2000年度诺贝尔物理奖授予三位科学家,他们是俄罗斯科学院圣彼得堡约飞技术物理研究所的Zh.I.Alferov、美国加利福尼亚大学的Herbert Kroemer和美国德克萨斯仪器公司的JackS.Kilby,以表彰他们为现代信息技术,特别是他们发明的高速晶体管、激光二极管和集成电路(芯片)所作出的奠基性贡献.Kilby由于发明并发展了集成电路技术而获奖,通过这项发明,微电子学成为所有现代技术的基础.Kilby的获奖成果已有另文(见2001年第3期《物理》)评述.Alferov和Kroemer则是由于他们在半导体异质结及其在电子和光电子学中的应用方面的突出贡献而获奖.该文仅就这两位诺贝尔物理奖得主在异质结及其在光电子中的应用方面的贡献进行评述.     

2000年诺贝尔物理奖

 根据瑞典皇家科学院１０月１０日发布的消息,瑞典皇家科学院已决定把２０００年度的诺贝尔物理奖授予在信息和通讯技术方面作出了基础性工作的３位科学家,其中的一半授予俄罗斯圣彼得堡Ａ．Ｆ约飞物理技术研究所的科学家泽罗斯·阿尔费罗夫（Ｚｈｏｒｅｓ Ｉ． Ａｌｆｅｒｏｖ）和美国加利福尼亚圣巴巴拉的加利福尼亚大学的科学家赫伯特·克勒默（ＨｅｒｂｅｒｔＫｒｏｅｍｅｒ）,以嘉奖他们研制了用于高速光电子学的半导体异质结结构;另一半授予美国得克萨斯达拉斯的得克萨斯仪器设备公司的科学家杰克·基尔比（Ｊａｃｋ Ｓ． Ｋｉｌｂｙ）,以嘉奖他在发明集成电路中的作用。     

阿耳费罗夫（Alferof，Zhores I，1930-）俄国物理学家（Physicist，Russia）

阿耳费罗夫主要从事半导体异质结构方面的研究工作，因而导致异质结晶体管、发光二极管和双异质结半导体激光器的发明。异质结晶体管的工作频率比普通晶体管高100倍，噪声小，适合做微波晶体管、高速开关管和光电晶体管。阿耳费罗夫因这方面的成就，与克勒默（Kroemer）分享Y2000年诺贝尔物理学奖。他曾来我国访问，并被南京大学聘为名誉教授。     

基尔比（Kilby，Jack S，1923-2005）英国物理学家（Physicist，England）

电子学的进一步发展是集成电路的发明，它开辟了微电子学时代。所谓集成电路，就是把多个晶体管和电阻、电容等元件做在同一半导体芯片上，互相连接，每块：占片实现一个单元电路的功能。集成电路的发明者是美国德州仪器公司的基尔比等。1958年夏，基尔比在一块硅片上集成了一个相移振荡器。基尔比选择在绝缘材料上沉积金为连接各元件的导线。由于发明集成电路，他被授予2000年诺贝尔物理奖的三分之一。     

俄国物理学家N.G.巴索夫去逝

20 0 1年 7月 1日 ,著名俄国物理学家Ｎ .Ｇ .巴索夫逝世 ,终年 78岁 .巴索夫和美国物理学家汤斯、俄国物理学普罗霍罗夫一起由于发明微波激射器、激光器和从事量子电子学方面的基础研究 ,获得过196 4年诺贝尔物理奖 .巴索夫 192 2年 12月 14日生于莫斯科南面 4 80公里的沃罗涅茨附近的乌斯曼 .194 1年在沃罗涅茨中学毕业 .卫国战争期间他在军队中服役 ,194 3年在基辅军医学校毕业 ,在军队中工作到 194 5年卫国战争胜利 .194 6年到 195 0年 ,在莫斯科机械学院学习 .从 194 8年起 ,巴索夫开始在前苏联科学院列别捷夫物理研究所的振荡实验室工…     

2002年诺贝尔物理奖

 2002年的诺贝尔物理奖使得天文研究领域再次成为人们关注的焦点。斯德哥尔摩瑞典皇家科学院宣布,2002年度的诺贝尔物理奖将授予雷蒙德·戴维斯(RaymondDavisJr,美国宾州大学物理天文系)、小柴昌俊(MasatoshiKoshiba,日本东京大学国际基本粒子物理中心)和里卡尔多·贾科尼(RiccardoGiacconi,美国华盛顿特区联合大学公司),以表彰他们在天体物理学领域的先驱性贡献。这里包括两项成就,前两位是因为宇宙中微子的探测,后一位是因为发现宇宙X射线源。     

1999年诺贝尔物理奖

 根据瑞典皇家科学院１０月１２日发布的消息,瑞典皇家科学院已决定把１９９９年度的诺贝尔物理奖授予两位荷兰科学家赫拉尔杜斯·霍夫特（Ｇｅｒａｒｄｕｓ’ｔＨｏｏｆｔ）和马丁努斯·韦尔特曼（ＭａｒｔｉｎｕｓＪ．Ｇ．Ｖｅｌｔｍａｎ）。这两位研究者是由于他们为粒子物理理论提供了更加坚实的数学基础而获奖的,尤其是揭示了用他们的理论如何精确计算物理量．欧洲和美国的粒子加速器近来进行的实验已经证实了他们的许多计算结果．数学基础更加坚实的粒子物理理论我们周围的一切物体都由原子构成,而原子又由电子和原子核组成．在原子核中有质子和中子,它们又都由夸克组成．为了研究夸克这一最深层次的情况,需要有大型加速器     

2003年的诺贝尔物理奖

2003年的诺贝尔物理奖授予了低温物理领域的三位物理学家，他们是Alexei A、Abrikosov(阿布里柯索夫)，Vitaly L．Ginzburg(京茨堡)以及Anthony J．Leggett(莱格特),此奖用以表彰前两者在超导电性方面的贡献，后者为在超流方面作出的贡献.大家知道，自然界中的微观粒子服从量子力学规律；     

肖克莱在硅谷的功绩和失误

肖克莱在硅谷的功绩和失误１９４７年，肖克莱（Ｗ．Ｓｈｏｃｋｌｅｙ）和Ｊ．Ｂａｒｄｅｅｎ，Ｗ．Ｂｒａｔａｉｎ一起发明了晶体管，他们当时都在新泽西州贝耳实验室（ＢｅｌＬａｂ．）工作．１９５６年他们获得了诺贝尔物理奖．肖克莱在发明晶体管后曾到加州理工学院任...     

瑞典皇家科学院通报(1992年10月14日)

瑞典皇家科学院决定把1992年诺贝尔物理奖授予法国巴黎高等物理化学学院和瑞士日内瓦欧洲核子研究中心的乔治斯·夏帕克教授,以表彰他对粒子探测器,特别是多丝正比室的发明和研制.物质最深层次的探测技术的一次突破今年诺贝尔物理奖授予法国的乔治斯·夏帕克,以表彰他对高能物理探测器的发明和研制.从1959年起,夏帕克在欧洲核子研究中心工作,这是欧洲建立在瑞士日内瓦州的粒子物理实验室.在那里,夏帕克发明了多丝正比室.这一开创性成果发表于1968年.主要由于他的工作,粒子物理学家才能够把他们的兴趣集中在非常罕见粒子的相互作用,这类相互作用往往揭示物质更深层次的奥秘.有时,在十亿个粒子的相     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.