用光导半导体开关产生高功率微波

由于光导半导体开关（ＰＣＳＳ）皮秒闭合和无抖动的优异特性，光控这种开关可产生高功率微波，本文描述了ＰＣＳＳ的三种工作模式及四种类型光作用微波源，并把它们与一般高功率微波源作了比较，最后，讨论了这类微波源的性能限制和发展前景。     

Nanosecond Laser-Driven Semiconductor Switch for 70 GHz Microwave Radiation

We study a new type of semiconductor switches for microwave radiation driven by laser emission. The switches comprise a plate of plain semiconductor built in a hollow metallic waveguide resonator. The plate can be illuminated by laser emission changing the resonator properties due to photoconductivity and therefore switching between two stable states. A sample switch has been built and experimentally investigated, demonstrating nanosecond level of switching performance. The results of numerical simulation by the FDTD method are compared with the experimental data. Typical laser pulse energies sufficient for switching are from 1 nJ to 100 nJ, switched radiation frequency tuning range is about 10 % around 70 GHz. The switching operation was observed in wide range of the driving 100-femtosecond laser parameters - for pulse energy from 6 pJ to 250 μJ, and laser emission wavelength from 0.75 μm to 2 μm.     

窄脉冲刚管调制器

雷达发射机和高功率微波装置对大功率刚管调制器的需求越来越大,尤其是窄脉冲调制器非常重要。随着大功率半导体开关器件技术的进步,窄脉冲刚管调制器逐渐变为现实。为了降低成本、满足系统小型化的要求,仅使用一个耐压900V的开关管,通过高变比脉冲变压器的耦合,就得到了脉冲宽度400ns、脉冲电压达到12kV的调制脉冲。     

Triggering GaAs lock-on switches with laser diode arrays

Progress toward the triggering of high-power photoconductive semiconductor switches (PCSSs) with laser diode arrays, is reported. An 850-W optical pulse from a laser diode array was used to trigger a 1.5-cm-long switch that delivered 8.5 MW to a 38.3-Ω load. Using 166-W arrays, it was possible to trigger a 2.5-mm-long switch delivering 1.2 MW with 600-ps rise-times at pulse repetition frequencies of 1 kHz. These 2.5-mm-long switches survived 10⁵ pulses at 1.0 MW levels. In single-pulse operation, up to 600 A was switched with laser diode arrays. The goal is to switch up to 5 kA in a single-shot mode and up to 100 MW repetitively at up to 10 kHz. At electric fields below 3 kV/cm GaAs switches are activated by creation of one electron-hole pair per photon. This linear mode demands high laser power and, after the light pulse, the carriers recombine in nanoseconds. At higher electric fields GaAs acts as a light-activated Zener diode. The laser light generates carriers as before, but the field induces gain such that the amount of light required to trigger the switch is reduced by a factor of up to 500. The gain continues until the field across the sample drops to a material-dependent lock-on field. The gain in the switch allows for the use of laser diodes     

Delay time in GaAs high-power photoconductive switches

The delay time defined as the time interval between the beginning of optical illumination and the onset of switching in photocurrent in gallium arsenide (GaAs) high-power photoconductivity switches is studied on the basis of electroabsorption caused by absorption edge shifting due to bandgap narrowing. The influences of the initial open-state field, the laser wavelength and the temperature are given. The results show it is the reflection and the transmission of the switch semiconductor slab indicated by the absorption fraction express the absorption rate of the illumination energy by the switch     

MEMS局部加热封装技术与应用

随着半导体技术的发展,封装集成度不断提高,迫切需要发展一种低温封装与键合技术,满足热敏器件封装和热膨胀系数差较大的同质或异质材料间的键合需求。针对现有整体加热封装技术的不足,首先介绍了局部加热封装技术的原理与方法,然后对电流加热、激光加热、微波加热、感应加热和反应加热等几种局部加热封装技术进行了比较分析,最后具体介绍了局部加热封装技术在热敏器件封装、MEMS封装和异质材料集成等方面的应用。由于局部加热封装技术具有效率高、对器件热影响小等优点,有望在MEMS技术、系统封装(SiP)、三维封装及光电集成等领域得到广泛应用。     

Burnout of semiconductor devices under the action of microwave pulses and electrical video pulses

The conditions for the energy equivalence of the effect of high-power microwave pulses and electrical video pulses on semiconductor devices are formulated and experimentally tested. The application of the video-pulse method is validated for the determination of parameters that characterize the hardness of micro-wave semiconductor devices against high-intensity electromagnetic interference capable of causing catastrophic failure.     

用于磁约束核聚变电子回旋共振加热系统的兆瓦级回旋管

磁约束核聚变能是目前人类认识到可以根本解决人类能源问题的重要途径之一。电子回旋共振加热(ECRH)和电流驱动(ECCD)是核聚变装置等离子体温度达到约1亿度稳定聚变条件的主要加热方式。而回旋管是ECRH系统高功率微波源的核心器件。本文针对磁约束核聚变能ECRH系统所需的高功率微波源介绍了国内外兆瓦级回旋管的技术发展、研究现状和发展趋势,并探讨了回旋管的未来研究方向。     

808nm波长锁定大功率半导体激光器列阵

大功率半导体激光器列阵(DLA)具有功率高、电光转换效率高、可靠性强、寿命长、体积小及成本低等诸多优点,但其波长随温度变化较大,光谱线宽较宽,这些缺点直接限制了其实际应用.为了解决此问题,采用体布拉格光栅(VBG)构成波长锁定大功率半导体激光器系统.体布拉格光栅可以把波长锁定,同时把光谱线宽压窄,从而有效改善了DLA波...     

Monolithically integrated high-power broad-band RF switch based on III-N insulated gate transistors

We report on the high-performance monolithically integrated RF switch based on metal-oxide-semiconductor III-N heterostructure field-effect transistors (MOSHFETs). The radio frequency (RF) switch microwave monolithic integrated circuit (MMIC) consists of three submicron-gate MOSHFETs connected into /spl pi/-type configuration. In the 0-10 GHz frequency range, the insertion loss is less than 1dB and the isolation is better than 20 dB. The switching powers well exceed 20 W per 1mm of the active element width. The high performance parameters of the switch are achieved due to unique properties of III-nitride MOSHFET, which combines a low channel resistance and high breakdown voltage features of AlGaN/GaN HFETs and extremely low gate leakage currents, large gate voltage swing and low gate capacitance specific to insulated gate design. The combination of these parameters makes MOSHFETs excellent candidates for high-power switching. The experimental data obtained from the RF switch are in close agreement with the results of simulations.     

Equivalent actions of high-power microwave and video pulses with different polarities on semiconductor diode structures

The energy, power, and temperature characteristics of semiconductor p-n junction structure and the structure with a Schottky barrier are simulated under the actions of a high-power microwave and video pulses with different polarities. The results of simulations are presented. The temperature fields are comparatively analyzed using the numerical model of drift-diffusion thermal approximation and the interval estimates of the energy equivalence under the actions of pulses of different types.     

大功率宽条分布反馈激光器研究

大功率半导体激光器一般用作抽运源,但其抽运的离子吸收峰带宽一般都比较小。为提高大功率半导体激光器对固体或光纤激光器等的抽运效率,就要降低半导体激光器的输出波长随注入电流和热沉温度的漂移系数。分析了光栅深度和光栅填充因子对激光器输出波长锁定效果的影响,实验验证确定出合适的光栅参数,依据优化条件得出合适的激光器腔长,制备出锁定效果良好的宽条分布反馈激光器。该激光器的单管腔长2.4mm,发光条宽100μm,连续最大输出功率400mW,热沉温度为15℃时的输出波长为954nm,输出波长随注入电流的漂移系数为0.67nm/A,输出波长的温漂系数为0.046nm/K。     

Impact of near-end residual reflectivity on the spectral performance of high-power pump lasers

Abnormal spectral characteristics are observed in high-power semiconductor pump laser modules with ultralow chip front-facet reflectivity levels. We have identified the root cause as destructive interference in an external-cavity reflection from an antireflection (AR) coated fiber tip. This suppressive external cavity imposes a practical limit on the lower desirable bound for front-facet AR coatings for high-power lasers and uncooled fiber Bragg grating stabilized semiconductor devices.     

半导体激光器散热技术研究及进展

在半导体大功率激光器的各种关键技术中,散热问题的解决是一个极其关键的技术。因为半导体激光器能产生很高的峰值功率,这些器件的电光转换效率为40%~50%,即所输入的电能50%~60%都转换为热能。在管芯焊接的地方产生的热流量大约为1KW.cm-2。这种热负载是限制激光器正常工作的关键因素。半导体激光器列阵与叠阵散热问题解决会直接关系到激光器的使用寿命,导致激光器有源区温度的迅速提高,从而引起激光器的光学灾变,甚至烧毁半导体激光器。大功率激光器列阵及叠阵在高功率的二极管泵浦固态激光器(DPSSL)系统中有很大的应用,市场发展潜力很大。因此,有必要发展大功率激光器列阵及叠阵。随着大功率激光器列阵及叠阵的迅速发展,与其有关的关键技术也应该加以研究。     

全金属化耦合封装的大功率半导体激光器模块

大功率半导体激光器模块对耦合封装工艺要求较高,耦合封装工艺直接影响模块的可靠性。采用金属化楔形微透镜光纤与大功率半导体激光器对准耦合,耦合效率达到87%;采用激光焊接定位的方式对大功率半导体激光器与楔形微透镜光纤进行耦合固定,实现了大功率半导体激光器模块的全金属化封装。通过环境考核试验证明,模块储存温度达到-60～120℃,能够满足许多特殊环境对半导体激光器模块的要求。     

Power conversion efficiency of semiconductor injection lasers and laser arrays in CW operation

In many applications it is important to optimize the power conversion efficiency of semiconductor lasers and laser arrays. A method for calculating this efficiency which takes into account temperature effects is described, and some calculated results are presented and discussed. It is found that under certain conditions, a small increase in the thermal resistance of the device can result in a large reduction of its efficiency. Temperature effects are important in high-power semiconductor lasers, and in particular in laser arrays, where low thermal resistance heat sinking may be crucial to the device operation.     

Comparison of interferometric all-optical switches fordemultiplexing applications in high-speed OTDM systems

We have investigated three interferometric all-optical switches based on cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), the semiconductor laser amplifier in a loop mirror (SLALOM) switch, the Mach-Zehnder interferometer (MZI) switch, and the ultrafast nonlinear interferometer (UNI) switch. Switching windows with different widths are measured under similar conditions for all three switching configurations. We introduce the integrated contrast ratio (ICR) as a measure to evaluate the performance of a switch from switching windows. Using the ICR, the switches are compared and their application is discussed as demultiplexer in optical time division multiplexing (OTDM) systems for data rates of 40, 80, and 160 Gb/s     

连续半导体激光器单条阵列老化筛选系统

介绍了用于连续高功率半导体激光器单条阵列的老化筛选系统,通过对积分球采集激光功率进行理论分析,确定了积分球内壳的参数.采用水冷积分球,实现了激光功率探测部分的冷却,同时解决了激光功率采集以及球壳内部散热的问题.利用光电探测器、数据采集卡等硬件实现了激光功率信号的光电转换以及模数转换,基于LabVIEW环境开发了激光功率...     

大功率半导体激光束非球面准直系统的优化设计

为实现空间激光束的远距离传输,利用矢量折射定理研究了大功率半导体激光器发散光束经非球面、非轴对称准直系统的光传输特性。对空间光线传输得出了矩阵传递公式,并针对大功率线源半导体激光器的发散光束进行了高精度的准直优化设计。为实现对激光束的进一步准直,利用光学设计软件CODE-V设计了卡塞格伦光学天线。利用两点法对发散角进行了实验测试,结果表明优化设计的准直系统发散角为1.924 mrad,经光学天线进一步准直后的发散角为96.2μrad。本空间光线追迹方法对复杂光学系统的精确计算具有一定参考意义,所设计的大功率线源激光束准直系统能广泛应用于远距离激光通信系统中。     

Radiation of Millimeter Waves from a Leaky Dielectric Waveguide with a Light-Induced Grating Layer

A theoretical analysis is presented for the radiation characteristics of millimeter waves in a periodic dielectric waveguide having a light-induced grating layer. The waveguide is assumed to be composed of an insulator (sapphire) slab whose one surface is coated with a high-resistivity semiconductor (silicon) film. A boundary-integral-equation formulation is employed to obtain characteristic solutions of the waveguide. Numerical calculations are made at 94 GHz for both TM and TE polarizations. Estimations of the illumination power required to produce the grating are given. The waveguide presented in this paper, in conjunction with a high-power semiconductor diode laser array as a light source, may be developed to operate as an electronically beam-steerable leaky-wave antenna at millimeter-wave frequencies.