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891.
We demonstrate a 165-mu;m oblate spheroidal microcavity with a free spectral range of 383.7 GHz (3.06 nm), a resonance bandwidth of 23 MHz (quality factor Q approximately 10(7)) at 1550 nm, and finesse F>/=10(4) . The highly oblate spheroidal dielectric microcavity combines a very high Q factor, typical of microspheres, with a vastly reduced number of excited whispering-gallery modes (by 2 orders of magnitude). The very large free spectral range in this novel microcavity-a few hundred gigahertz instead of a few gigahertz as in typical microspheres-is desirable for applications in spectral analysis, narrow-linewidth optical and rf oscillators, and cavity QED. 相似文献
892.
Baryon rapidity loss in relativistic Au + Au collisions 总被引:4,自引:0,他引:4
Back BB Betts RR Chang J Chang WC Chi CY Chu YY Cumming JB Dunlop JC Eldredge W Fung SY Ganz R Garcia E Gillitzer A Heintzelman G Henning WF Hofman DJ Holzman B Kang JH Kim EJ Kim SY Kwon Y McLeod D Mignerey AC Moulson M Nanal V Ogilvie CA Pak R Ruangma A Russ DE Seto RK Stanskas PJ Stephans GS Wang HQ Wolfs FL Wuosmaa AH Xiang H Xu GH Yao HB Zou CM 《Physical review letters》2001,86(10):1970-1973
An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that display a broad peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a stationary source at midrapidity decreases with increasing beam energy. The data suggest that the stopping is substantially less than complete at these energies. 相似文献
893.
A new idea of using change in index of refraction to suppress gain variation in a saturated semiconductor optical amplifier (SOA) is presented. This kind of gain compensation has the advantage of high speed because it involves two phenomena that always accompany each other. This compensation can be achieved with a nonsymmetrical Mach-Zehnder interferometer structure. Calculated results show that with this structure the input and output power of the SOA can be extended to nearly 10 dB from the former small-signal limit when less than 1-dB gain variation is permitted. Numerical simulations with an advanced dynamic model of the SOA agree with the calculated results. 相似文献
894.
以硅纳米孔柱阵列(Si-NPA)为衬底、用化学气相沉积法制备了具有规则阵列结构特征的ZnO/Si-NPA纳米复合体系,并对其结构和光致发光性质进行了表征. 实验结果显示,组成ZnO/Si-NPA表面阵列的每个柱子均呈现层壳结构. 不同于衬底Si-NPA的红光和蓝光发射,ZnO/Si-NPA在紫外光区和蓝绿光区呈现出两个强的宽发光峰. 分析表明,紫外光发射应归因于ZnO晶体的带边激子跃迁;而蓝绿光发射则来自于ZnO晶体本征缺陷所形成的两类深能级复合中心上载流子的辐射跃迁. 相似文献
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Chengyun Cui Zuoxing Guo Yuhua Liu Qiongqiong Xie Zheng Wang Jiandong Hu Yuan Yao 《Optics & Laser Technology》2007,39(8):1544-1550
Co-based alloy coating was deposited on tool steel by powder feeding laser cladding. Sections of such coatings were examined to reveal their microstructures and phases using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results showed that the prime phase (γ-Co dendrite) and other phases, including Cr23C6, Co7W6, and CrNi existed in the coatings. Some different solidification morphologies, such as planar (at the interface), cellular and dendrite formed, varying from the interface to the surface. Fine microstructures of γ-Co dendrite and lamellar eutectic in dendritical regions strengthened the coatings. Besides, the effects of aged treatment on the microstructure and microhardness of the surface coating were studied. Aged treatment led to the precipitations of some carbide particles (Cr7C3 and Co3C) and boride particles (Co4B) from the cladded coating, causing an increase in microhardness in the laser-cladded coating. 相似文献