共查询到20条相似文献,搜索用时 306 毫秒
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为了有效降低偶氮苯聚合物薄膜全光开关信号的本底,提高全光开关信号的调制深度,利用线偏振光合成圆偏振光的原理,设计了一种新的线-圆双偏振态光束抽运光路。实验用532 nm光作为抽运光,632.8 nm的He-Ne激光作为探测光。532 nm的光先分为功率相等但偏振正交、相位差为π/2奇数倍的两束线偏振光,然后再合成一束抽运光。通过调制其中的一束来实现线偏振与圆偏振抽运光之间的转换,从而实现样品光致双折射的产生与擦除。以掺杂分散红1(DR1)的聚甲基丙烯酸甲酯薄膜(PMMA)为样品进行实验。结果表明,用此光路,样品全光开关信号的调制深度达到92%,远远高于传统的单一线偏振光束抽运光路的实验结果。 相似文献
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偶氮苯聚合物薄膜光致表面调制效应研究 总被引:1,自引:1,他引:0
实验观测了偶氮苯聚合物薄膜在Ar^ 激光(488nm)激发下的光表面调制效应。给出了488nm激光激发条件下,含有不同偶氮苯侧基的聚合物的光表面调制效应的数值。分析比较了偶氮苯聚合物表面调制效应的强弱及其产生的原因。给出光表面调制效应与聚合物接枝率的关系。 相似文献
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偏振光照对偶氮苯侧链聚硅氧烷膜表面能的提高 总被引:3,自引:2,他引:1
采用硅氢加成法合成了含偶氮苯侧链的聚硅烷液晶聚合物,用FTIR、DSC和偏光显微镜对聚合物结构及液晶特性进行了表征。采用473nm偏振光对聚合物膜进行了光致取向,用偏光显微镜对取向结果进行了表征,发现偏振光倾斜照射后侧链偶氮苯基团发生了面外垂直取向。采用量高法测量了取向前后膜的接触角,根据接触角计算了膜的表面能。聚合物膜在取向前接触角为94.5°,偏振光照射取向后降低为76.5°,表明光照使聚合物膜从疏水变为亲水,膜的表面能明显增加。结合锥光显微镜观察到的干涉图结果,提出了极性偶氮苯基团面外垂直排列取向提升膜表面能的机理。 相似文献
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光吸收调制微加工技术中偶氮材料光吸收率的时间变化特性 总被引:1,自引:0,他引:1
基于偶氮材料光吸收调制的高分辨率微加工技术近年来引起了极大关注。为揭示该技术中偶氮材料光吸收调制的机制,结合偶氮材料光致异构原理,利用偶氮材料的光吸收理论模型,数值模拟了偶氮材料光吸收率的时间变化特性。以典型偶氮苯染料分散黄7(Disperse Yellow 7-DY7)为例,分别开展了在365 nm光束单独作用和365 nm与532 nm双光束共同作用下,不同厚度DY7薄膜在365 nm光吸收率的时间变化特性实验研究。结果表明,在365 nm光束作用下,偶氮苯材料对365 nm光吸收率因光致异构效应发生了明显改变,而实验中532 nm光束的热效应对偶氮苯材料的光吸收率有显著的影响。 相似文献
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Metze G.M. Bass J.F. Lee T.T. Cornfeld A.B. Singer J.L. Hung H.-L. Huang H.C. Pande K.P. 《Electron Device Letters, IEEE》1990,11(1):24-26
State-of-the-art, 60-GHz, low-noise MMICs based on pseudomorphic modulation-doped FETs, with 0.25-μm×60-μm gates offset 0.3 μm from the source ohmic, are discussed. Single-state low-noise amplifiers (LNAs) exhibited minimum noise figures of 2.90 dB with 4.1 dB of associated gain at 59.25 GHz. Dual-state MMICs had minimum noise figures of 3.5 dB and 10.8 dB of associated gain at 58.50 GHz. Cascaded four-stage LNAs (two dual-stage MMICs) had minimum noise figures of 3.7 dB and over 20.7 dB of associated gain at 58.0 GHz. Finally, when biased for maximum gain, the four-stage amplifier exhibited over 30.4 dB of gain at 60.0 GHz 相似文献
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Very efficient X -band MESFET power amplifiers, showing greater power-added efficiency over a wider bandwidth than any X -band amplifiers of comparable output reported to date, are discussed. The amplifiers were designed with attention given to optimum bias, proper harmonic termination, and efficient power combining. These device and design issues are discussed, and a straightforward design method which achieved the increased levels of efficiency is described 相似文献
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双频CO_2激光多光子离解CF_3CHCl_2分离氘 总被引:2,自引:0,他引:2
本文研究在双频CO_2激光辐照下CF_3CDCl_2-CF_3CHCl_2混合气的多光子离解。所获得的氘的一步浓缩系数β_(产物)达1600,比单频CO_2激光辐照下离解的浓缩系数大。 相似文献
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《中兴通讯技术(英文版)》2010,(4):I0001-I0002
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New classes of nonrecursive linear digital filters are proposed as alternatives to conventional methods for digital signal processing devices. In fact, the traditional approach, where signal samples are represented by 8-15 bit words, can be very expensive to implement due to the complexity of multibit multipliers and adders. Filter structures consisting of a transversal filter with tap coefficients restricted to - 1, 0, or + 1 and cascaded with simple recursive sections are proposed. Using a mean square error criterion, dynamic programming methods to select optimum sets of coefficient values for the taps are presented and evaluated. It is shown that these structures lend themselves to very simple hardware implementations and offer a valid alternative to the conventional filtering approach. Designs for several example filters are presented, and their implementation complexity is examined. 相似文献
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Wallace Ly 《电子设计技术》2005,12(1):94-94
白光LED驱动器的主要构件是一个振荡器,一个电荷泵和一个稳流电流源。美国国家半导体公司(WWW.national.com)生产一种在高度集成的LM2791/2型IC内包含以上三种构件的器件。白光LED驱动器通常与手机基带控制器或微控制器串联使用。你可以方便地采用LM2791/2来提供一个时钟源:你只要考虑到在快速充放电电容器(C1)两个引脚上有一个伪方波,就可以实现一个简单而有用的电路。 相似文献