OnceAS/Q:一个面向QoS的Web应用服务器

网络分布计算环境下应用系统的需求多样化和复杂性的增长,要求位于中间件层次的Web应用服务器(web application server,简称WAS)从原来的尽力而为服务模型转变为服务质量(quality of service,简称QoS)保障模型,为具有不同需求的应用分别提供适宜的服务质量保障.目前的WAS系统在此方面仍然比较薄弱.OnceAS/Q是一个面向QoS的WAS系统,它以QoS规约为基础,为不同应用提供不同的QoS保障能力.OnceAS/Q实现了一个应用QoS保障框架,提供了一组QoS服务组件支持具有QoS需求的应用开发和运行.介绍了OnceAS/Q的体系结构和主要组件,详细阐述了两个关键问题,一是QoS规约的定义及其映射,另一个是面向QoS的服务组件和资源的动态重配.OnceAS/Q原型在Ecperf测试基准下,对其QoS保障能力进行了实验.实验数据表明,在较大规模的应用环境下,OnceAS/Q能够提供更好的服务质量,并且开销是可接受的.

On-Chip All-Optical Passive 3.55 Gbit/s NRZ-to-PRZ Format Conversion Using a High-Q Silicon-Based Microring Resonator

We report the experimental result of all-optical passive 3.55 Gbit/s non-return-to-zero (NRZ) to pseudo-return-to-zero (PRZ) format conversion using a high-quality-factor (Q-factor) silicon-based microring resonator notch filter on chip. The silicon-based microring resonator has 23800 Q-factor and 22 dB extinction ratio (ER), and the PRZ signals has about 108 ps width and 4.98 dB ER.

Stress and resistivity controls on in situ boron doped LPCVD polysilicon films for high-Q MEMS applications

The simultaneous control of residual stress and resistivity of polysilicon thin films by adjusting the deposition parameters and annealing conditions is studied. In situ boron doped polysilicon thin films deposited at 520 ℃ by low pressure chemical vapor deposition (LPCVD) are amorphous with relatively large compressive residual stress and high resistivity. Annealing the amorphous films in a temperature range of 600-800 ℃ gives polysilicon films nearly zero-stress and relatively low resistivity. The low residual stress and low resistivity make the polysilicon films attractive for potential applications in micro-electro-mechanical-systems (MEMS) devices, especially in high resonance frequency (high-f) and high quality factor (high-Q MEMS resonators. In addition, polysilicon thin films deposited at 570 ℃ and those without the post annealing process have low resistivities of 2-5 mΩ·cm. These reported approaches avoid the high temperature annealing process (> 1000℃), and the promising properties of these films make them suitable for high-Q and high-f MEMS devices.

Efficient Mode-locked and Q-switched Nd∶YVO_4 Laser with Semiconductor Saturable Absorber Mirror

We reported an efficient diode pumped Nd ! YVO, 1 064 nm laser passively mode-locked and Q-switched by a semiconductor saturable absorber mirror(SESAM). At the incident pump power of 7. 5 W, 2. 81 W average output power was obtained during stable CW mode locking with a repetition rate of 111 MHz. The optical conversion efficiency was 37. 5% , and the slope efficiency was 39%. So far as we know, this is the highest optical-optical conversion efficiency with a SESAM at home.

中间镜式半导体可饱和吸收镜在Nd:YVO_4激光器中被动调Q特性研究

利用一种新型的中间镜式半导体可饱和吸收镜，成功实现了二极管泵浦Nd

低温生长GaAs在Nd:YVO4激光器中调Q特性的研究

采用一种新型的被动调Q饱和吸收体,低温生长GaAs薄膜,实现了半导体抽运Nd:YVO4激光器的调Q运转.研究了激光器的调Q特性,调Q抽运阈值为2W.在抽运功率9.2 W时,获得的最短脉冲半峰全宽为15 ns,最大单脉冲能量为4.84 μJ,最高峰值功率为330 W,最大平均输出功率为1.16 W;脉冲重复频率在220 kHz到360 kHz之间.

低温GaAs被动调Q锁模Nd：Gd0．42Y0．58VO4混晶激光器特性研究

采用低温生长GaAs晶体作为被动饱和吸收体兼输出镜,实现了Nd∶Gd0.42Y0.58VO4混晶激光器的调Q锁模运转。研究了Nd∶Gd0.42Y0.58VO4激光器的基频运转特性。在输出镜透射率T=10%、腔长L=40 mm的情况下,当抽运功率为8.6 W时,获得激光输出功率3.78 W,光光转换效率为43.9%。并测量了Nd∶Gd0.42Y0.58VO4混晶被动调Q激光器的输出特性。实验结果表明激光器调Q运转阈值为2 W,当抽运功率为3.7 W时,激光器出现调Q锁模行为;当抽运功率为8.6 W时,激光器调Q锁模深度达70%以上,对应的脉冲包络重复频率为670 kHz,半峰全宽为180 ns,平均输出功率为1.35 W,光光转换效率为15.7%。

透射式SESAM实现掺Yb^3＋光纤激光器被动调Q锁模

锁模光纤激光器具有体积小、性能稳定及模式好等优点，日益受到关注。利用一种新型的透过式半导体可饱和吸收镜，实现双包层掺Yb^3＋光纤激光器调Q锁模脉冲激光输出。得到的脉冲调Q包络半高宽约500ns，重复频率110kHz，平均输出功率45mW，锁模脉冲重复频率26．7MHz。锁模光路比反射式吸收镜更简单，易于调节，为进一步引入色散补偿元件进行飞秒脉冲的实验研究奠定了基础。

用表面态型半导体可饱和吸收镜实现Yb∶YAG激光器被动调Q锁模

制作了一种新型的半导体可饱和吸收镜--表面态型半导体可饱和吸收镜.用表面态型半导体可饱和吸收镜作为被动锁模吸收体实现了半导体端面泵浦Yb∶YAG激光器被动调Q锁模.在泵浦功率仅有1.4 W的情况下,获得了调Q锁模脉冲序列,锁模平均输出功率1 mW,锁模脉冲重复频率200 MHz.

Passive Q-switching of diode-pumped Yb:YAG microchip laser with ion-implanted GaAs

We reported a passive Q-switched diode laser pumped Yb:YAG microchip laser with an ion-implanted semi-insulating GaAs wafer. The wafer was implanted with 400-keV As^(+) in the concentration of 10^(16) ions/cm^(2). To decrease the non-saturable loss, we annealed the ion-implanted GaAs at 500 oC for 5 minutes and coated both sides of the ion-implanted GaAs with antireflection (AR) and highreflection (HR) films, respectively. Using GaAs wafer as an absorber and an output coupler, we obtained 52-ns pulse duration of single pulse.