二极管抽运Nd∶YAG薄片激光器研究

报道了采用脉冲二极管抽运的高功率薄片激光器。通过合理设计泵浦光四通薄片增益介质面泵浦耦合系统,实现了泵浦光在薄片增益介质的均匀泵浦;通过实验实现了1.2 kW的激光输出,光-光转换效率25%。     

端面抽运板条放大器抽运均匀性和热效应模拟

为了使激光二极管抽运的全固态激光器能够得到高光束质量、高功率的激光输出,对激光介质的温度分布和热透镜效应的研究很重要。利用ZEMAX软件的非序列模块,根据光束追迹的方法模拟了端面抽运结构下,高功率二极管抽运激光放大器的抽运光在增益介质中的光场分布情况。结果表明,此抽运方式下光场分布均匀。将激光介质中吸收的抽运光体功率密度分布结果代入LAS-CAD软件,计算出在种子光未注入和注入情况下,抽运功率为2400W时,增益介质最大温差分别为68℃,54.7℃以及最大热应力分别为90N/mm2,67N/mm2,因此当抽运功率小于2400W,运转的全过程对于激光增益介质是没有威胁的。该模拟结果对于高功率二极管抽运板条激光放大器的设计具有一定参考价值。     

掺钛蓝宝石晶体激光放大实验研究

报道了掺钛蓝宝石晶体激光放大实验研究，实验中得到最大的单程放大和双程放大增益分别为１４．７６和２６．３１，对应双程放大的增益系数为１．８１ｃｍ－１，并由此推算出掺钛蓝宝石晶体的增益截面为２．７４×１０－１９ｃｍ２，饱和能量密度为０．９３Ｊ／ｃｍ２．并给出不同的泵浦能量密度所对应的最佳放大介质长度。实验表明小信号近似下，放大增益只与泵浦功率密度有关．与注入种子能量无关。实验还测量了掺钛蓝宝石晶体对不同波长种子光的放大增益。     

热容模式下片状激光介质瞬态温度及热应力分析

为了研究激光介质热畸变对固体热容激光器的影响,数值计算了高功率激光二极管阵列抽运片状激光介质的瞬态温度场和热应力分布。结果表明,在相同的抽运功率密度下,激光介质中的温度分布和热应力分布不仅与激光介质几何构型及抽运光空间分布有关,还与抽运光斑在介质表面的填充因子密切相关。当抽运光斑未充满激光介质时,介质的表面靠近边缘处会出现大的拉应力集中,并且介质表面的最大轴向位移和最大拉应力随光斑填充因子增大而增大;而当抽运光充满介质时,表面是压应力,较小的拉应力存在于介质内部。     

核泵浦~3He-Ne激光增益实验

在稳态核反应堆上,测定了热中子辐照下,~3He-Ne激光体系(P_(He:P_(Ne)=5:1,P_总=4×10~4Pa)的增益系数(丸=632.8nm,跃迁3S_2-2P_4)。当热中子通量为2×10~(12)n/cm~2·时,其增益系数为1.7×10~(-2)/cm。研究了增益系数随热中子通量的变化关系,讨论了温度对增益的影响。实验表明核泵浦~3He-Ne体系有可能实现激射。     

氩离子激光泵浦钛宝石输出超过1W

最近中科院物理所利用连续波氩离子激光泵浦φ6×12mm钛宝石棒,采用四镜Z型腔,所用宽带介质膜中心波长为750nm,当泵浦光12W时,总输出超过1W。采用双折射滤光片调谐时,获得730～810nm     

短蒸气室自加热碱金属激光器输出特性

短蒸气室自加热碱金属激光器的原理是利用未被增益介质吸收的抽运光加热碱金属蒸气室。基于三能级速率方程,建立了半导体激光双端抽运碱金属激光器的理论模型,研究了增益介质长度、蒸气室温度和抽运源线宽等参数对短蒸气室自加热碱金属激光器输出激光的影响。研究结果表明,在普通外腔半导体激光器抽运下,增益介质长度为2mm时可以实现瓦级激光输出,选择较高的抽运光功率可提高自加热碱金属激光器的输出功率。该研究结果将为自加热碱金属激光器的实验提供理论基础,并可进一步拓展小功率碱金属激光器的应用领域。     

Ce∶KNSBN光折变光纤两波耦合特性研究

研究了掺铈钾钠铌酸锶钡 (Ce∶KNSBN)光折变光纤“扇”特性及两波耦合的基本特性。通过实验发现 ,当入射光的入射角为 8°左右时 ,“扇”最小 ,这与块状晶体有根本的不同。在信号光与抽运光的入射夹角 2θ小于 11°时 ,两波耦合增益随入射夹角的增大而增大 ,而当入射夹角大于 11°时 ,两波耦合增益随着入射夹角的增大而迅速减小。给出了在各个不同的入射夹角下 ,两波耦合增益中透射的信号光的时间特性曲线。两波耦合增益随信号 抽运比的增加而增加 ,在入射夹角为 8° ,信号 抽运比为 1∶10 0 0时 ,两波耦合增益达到了 77,比块状晶体相应条件下提高了 4倍。用两波耦合的理论公式对增益随信号 抽运比的实验数据进行了拟合 ,二者相符     

热容模式下片状激光介质的热畸变

利用有限元数值方法,模拟计算了热容模式下片状激光介质的瞬态温度分布和热应力分布及其波前畸变和应力双折射。结果表明:激光介质中的温度分布和热应力分布与抽运光斑及介质的几何形状密切相关。当抽运光斑未充满激光介质时,介质的表面靠近边缘处会出现大的拉应力集中,并且介质中最大拉应力和表面的最大轴向位移随抽运光斑尺寸缩小而增大;而当抽运光充满介质时,表面是压应力,较小的拉应力存在于介质内部。介质变形和热光效应(折射率随温度变化)是产生波前畸变的主要原因。热应力双折射对光束产生较大的退偏作用,从而影响激光器的输出性能。     

LD侧面抽运的Nd∶YAG激光器抽运均匀性研究

通过对激光二极管 (LD)侧面抽运激光介质的分析研究 ,建立了二极管侧面抽运激光介质所吸收的抽运光功率分布的数学模型。采用光线追迹法模拟计算出单个二极管在不同抽运参数下直接抽运激光棒时 ,激光棒所吸收的抽运光功率的分布。比较了介质的吸收系数和二极管到激光棒距离的不同给抽运的均匀性带来的差异。计算了在有冷却系统的条件下 ,多个二极管阵列抽运时的抽运光功率分布 ,得到了较好的抽运均匀性     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first     

JOURNAL OF ELECTRONICS(CHINA)

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NEXT GENERATION WIRELESS NETWORKS–ESPECIALLY THE USE OF MILLI-MICROWAVE BANDS

The global bandwidth shortage of wireless communications has motivated the exploration of the naillimeter wave （ram-wave） frequency spectrum for the next generation wireless communications. Recent advances in RF CMOS technology and high speed baseband signal processing technologies have enabled tile extensive research and development of turn-wave wireless communications. The multi gigabit per second data rate of ram-wave system will lead to applications in many important scenarios, such as WPAN, WLAN,back-haul for cellular system. And the frequency bands include 28 GHz, 38 GHz, 45GHz, 60GHz, E-BAND and even beyond 100 GHz. The propagation and the imitation of the RF circuits design in these frequency bands make the directional antennas be inevitable for mm-wave communications.