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本文通过菲涅耳-基尔霍夫衍射积分方法,推导了一般稳定和非稳定球面镜谐振腔中自再现模的解析表达式,揭示了从稳定腔变为非稳腔过程中自再现模的变化规律.进一步地,本文在几何光学近似条件下得到了非稳腔的自再现模,通过与衍射积分结果对比,发现基于几何光学近似得到的非稳腔最低阶偶对称模(即基模)和最低阶奇对称模的空间分布与衍射积分结果一致.而对于更高阶的自再现模,当非稳腔接近稳定腔时,几何光学近似得到的自再现模空间分布和衍射积分结果之间存在较大差异.本文的结果可以作为激光原理教学内容的重要补充. 相似文献
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目前半导体锗在吸收边附近(1550 nm)的压力-折射率系数在实验和理论上并未研究清楚.本文通过测量在不同压力下镀在光纤端面的高结晶度锗薄膜的反射率,来计算得到锗在吸收边附近的压力-折射率系数.本文的实验结果显示,锗在吸收边附近出现反常色散现象,即折射率随能量变化呈正相关,并且其压力-折射率系数出现反常,为正值,这是由于多晶结构中的激子吸收所引起.通过引入描述激子色散的临界点模型,得到锗在吸收边附近的反常色散范围和压力-折射率系数呈正值的范围.本文的结果将有助于基于锗薄膜的通信C波段光学器件的研究. 相似文献
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将三角帆蚌的肌肉凝集素粗提液与动物(草鱼、兔、老鼠、家鸡)及人的A、B、O、AB型共8种血红细胞悬液和部分细菌(枯草芽孢杆菌、金黄色葡萄球菌、大肠杆菌)菌体进行凝集反应以检测其凝集活性,同时进行糖抑制、热稳定性及pH影响试验.结果表明:三角帆蚌肌肉凝集素能凝集实验用的8种红细胞,其中对兔红细胞凝集活力最强,为25;不能和供试的3种微生物发生凝集反应;三角帆蚌凝集索粗提物在pH 6.O-8.0之间有凝集活性,在pH 7.4时凝集活性最强;温度4-50℃,三角帆蚌凝集素都具有活性,处于20℃和30℃左右温度时的凝集素活力最强,60℃的水浴加热后凝集素完全失活;三角帆蚌凝集素凝集活性可被2.5 mg/mL的麦芽糖所抑制,而D-葡萄糖、D-果糖、蔗糖、乳糖则无影响. 相似文献
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基于延迟抖动的流媒体传输QoS机制 总被引:1,自引:0,他引:1
着眼于流媒体的传输服务质量问题,研究给定网络条件下流媒体的自适应传输策略,提出了一种基于延迟抖动的流媒体传输QoS(Quality of Service)方法。仿真实验表明该方法能够迅速判断网络状态,使流媒体的数据传输与网络当前状态及时吻合,能够获得较低丢包率的同时获得较大数据传输 相似文献
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碳酸氢铵与氯化钇反应及结晶产物的组成和晶相类型 总被引:5,自引:0,他引:5
The relationships of crystal type, crystallization speed, purity, grain size and shape of rare earth carbonate with precipitation and crystallization conditions are very important for the production of rare earth carbonate with high efficiency, high quality and low cost. It is necessary for us for further understand the crystallization process mechanism and the factors effect on the crystallization. In the present paper, the crystallization characteristic, composition and crystal phase type of yttrium carbonates or ammonium yttrium carbonates precipitated from yttrium chloride solution using ammonium bicarbonate as precipitant were determined by chemical analysis, X-ray powder diffraction and the pH situ-determination. It was found that the crystal phase type was dominated by the feed molar ratio of ammonium bicarbonate to yttrium chloride, and the crystallization speed and the crystal composition were also influenced by temperature, feed manner and aging period etc. When precipitating and aging under lower temperature, crystallization is easy to take place in the high feed molar ratio zone, and when increasing tempera-ture, crystallization will take place both in lower and higher feed molar ratio zones. The results show that spherical yttrium carbonate with tengerite type crystal phase can be formed within the temperature 30~70℃ when feed molar ratio of ammonium bicarbonate to yttrium chloride is less than 4, and that a rhombus flake crystal, which possesses the composition of ammonium yttrium quasi-double carbonate and a new XRD pattern, is formed when the feed molar ratio is over 4. Their compositions can be represented as (NH4)aY(CO3)b(OH)c·nH2O, a< 1, 1< b< 2, c=3+a-2b. A fine crystal of ammonium yttrium double carbonate with the formula of (NH4)Y(CO3)2·H2O can also be obtained as using an enough amount of ammonium bicarbonate and aging enough time. 相似文献
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Measuring Carrier-Envelope Phase of Few-Cycle Laser Pulses Using High-Order Above-Threshold Ionization Photoelectrons 下载免费PDF全文
We experimentally demonstrate the measurement of carrier-envelope phase of few-cycle laser pulses. We have built a stereo above-threshold ionization setup. The photoelectron energy spectra of high-order above-threshold ionization are measured in both the left and right directions in the linearly polarized laser fields. It is shown that the left-right asymmetry of the spectra is dependent on carrier-envelope phase of few-cycle laser pulses. Two asymmetry parameters from the low-energy and high-energy regions at the above-threshold ionization plateau map a phase ellipse, in which the points indicate the absolute value of carrier-envelope phase. We have calibrated the phase ellipse by comparison with the semiclassical calculation. This setup allows us to determine the value of the absolute phase of few-cycle laser pulses. 相似文献
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