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本文研究了Cu:KNSBN晶体光折变材料参量的温度特性.用光折变理论分析了文献6给出的Cu:KNSBN晶体两波耦合增益系数Γ随2θ在不同温度下的变化关系.得出了该晶体有效电荷密度Neff,有效电光系数和电子-空穴对抗因子乘积Rreff随温度的变化关系. 相似文献
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弱双折射光纤布喇格光栅反射偏振对温度响应特性的研究 总被引:1,自引:0,他引:1
理论分析了切趾弱双折射光纤布喇格光栅反射偏振相关特性与温度之间的关系.数值模拟了切趾弱双折射光纤光栅的反射谱、偏振相关损耗和差分群时延随波长变化曲线.实验测出了不同温度下反射谱、偏振相关损耗和差分群时延随波长变化曲线.根据实验结果对偏振相关损耗和差分群时延的变化情况作出了分析.反射偏振相关损耗呈现两个峰值,随温度增加两峰漂移程度相同,表明偏振相关损耗无明显差异.差分群时延最大值随温度增加成线性向长波方向漂移,证明了光纤光栅正交模损耗变化的等同性.综合理论分析与实验结果表明:切趾弱双折射光纤布喇格光栅的偏振特性随温度产生明显的变化,其正交模变化呈现等比例特性. 相似文献
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使用基于密度泛函微扰理论的第一原理赝势法, 计算了纤锌矿结构2H-SiC晶体在强激光照射下的电子特性, 分析了其能带结构和电子态分布. 计算结果表明: 2H-SiC平衡晶格参数a 和c随电子温度Te的升高逐渐增大; 电子温度在0–2.25 eV范围内时, 2H-SiC仍然是间接带隙的半导体晶体, 当Te超过2.25 eV达到2.5 eV以上时, 2H-SiC变为直接带隙的半导体晶体; 随着电子温度升高, 导带底和价带顶向高能量或低能量方向发生了移动, 当电子温度Te大于3.5 eV以后, 价带顶穿越费米能级; 电子温度Te在0–2.0 eV变化时, 带隙随电子温度升高而增大; Te在2.0–3.5 eV范围变化时, 带隙随电子温度升高而快速地减少, 表明2H-SiC晶体的金属性随电子温度Te的继续升高而增强. 在Te =0, 5.0 eV 处, 计算了2H-SiC晶体总的电子态密度和分波态密度. 电子结构表明Te =0 eV 时, 2H-SiC 是一个带隙为2.3 eV的半导体; 在Te =5.0 eV时, 带隙已经消失而呈现出金属特性, 表明当电子温度升高时晶体的共价键变弱、金属键增强, 晶体经历了一个熔化过程, 过渡到金属状态. 相似文献
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利用传输矩阵法研究了含特异材料的一维超导光子晶体的带隙特性. 研究表明, 这类超导光子晶体同样具有由传统的电介质材料构成的超导光子晶体一样的低频带隙, 且在一定的参数下该低频带隙可以相当宽. 但在一定的结构参数下, 这类超导光子晶体同完全由传统的电介质构成的光子晶体一样不存在低频带隙. 还就超导光子晶体的偏振特性、光子晶体结构参数及环境温度的变化对光子带隙结构的影响进行了研究.
关键词:
超导光子晶体
传输矩阵法
特异材料
光子带隙 相似文献
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使用基于密度泛函微扰理论的第一性原理赝势法, 模拟研究了纤锌矿6H-SiC晶体在强激光照射下电子特性的变化. 研究结果表明, 电子温度Te在升高到3.89 eV及以上后, 6H-SiC由间接带隙的晶体变为直接带隙的晶体; 带隙值随电子温度Te升高先是增大后又快速减小, 当电子温度Te大于4.25 eV以后, 带隙已经消失而呈现出金属特性. 相似文献
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石英晶体温度效应对四频差动激光陀螺中光场偏振特性的影响 总被引:1,自引:0,他引:1
为研究石英晶体温度效应对四频差动激光陀螺的影响,从陀螺的自再现传播矩阵出发,结合石英晶体旋光率随温度变化的经验公式,利用琼斯矩阵求本征模的方法,得出了四频差动激光陀螺腔内光场本征偏振态与温度的关系并进行了数值分析,得到椭圆度和左右旋差损随温度变化的曲线。结果表明,石英晶体温度效应对偏振特性的影响与反射镜片的振幅反射率和反射相移有密切关系,对于典型陀螺参量,在-60℃~60℃范围内石英晶体温度效应导致左右旋差损从0增加至10-6量级, 椭圆度从0.122增至0.138。 相似文献
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L. Btter-Jensen N. Agersnap Larsen V. Mejdahl N. R. J. Poolton M. F. Morris S. W. S. McKeever 《Radiation measurements》1995,24(4):535-541
Retrospective dosimetry using optically stimulated luminescence (OSL) on quartz extracted from (for example) bricks needs to account for strong OSL sensitivity changes that are known to occur depending on the previous thermal treatment of the sample. Non-heated quartz exhibits OSL orders of magnitude less per unit radiation than that for heated material. The reason these temperature-induced sensitivity changes occur in quartz is presently not well understood. This phenomenon is also seen in the related area of luminescence dating in which sedimentary quartz and quartz from heated archaeological samples show very different OSL sensitivities. In this paper we report on studies of the effects of high temperature annealing on the OSL and phototransferred TL (PTTL) signals from sedimentary and synthetic quartz. A dramatic enhancement of both OSL and PTTL sensitivity was found especially in the temperature range 500–800°C. Computer simulations of the possible effects are shown to produce data that agree in all essential details with the experimental observations. It is further demonstrated that the enhanced OSL sensitivity as a function of annealing temperature is not a pre-dose effect. 相似文献
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运用折射率椭球分析晶体的弹光效应,给出了三方晶系沿光轴方向的应力与折射率的变化关系.针对晶体的各向异性和折射率随应力变化很小的因素,利用白光干涉技术空间分辨率高的特点,将白光干涉技术拓展到研究各向异性材料的光学性质. 并对测量群折射率的光纤迈克尔逊白光干涉技术进行了改进.采用光栅位移传感器和全保偏光纤提高反射扫描镜的位移准确度.通过测量石英晶体在不同外力下折射率的变化情况,确定了晶体的弹光系数. 石英晶体的弹光系数P33和P13分别为0.110和0.279,其准确度达到0.001. 相似文献
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采用双球镜准光腔、频谱仪和锁相返波管组建了D波段低损耗介质测试系统,该系统通过频谱仪和外置谐波混频器得到腔体谐振测试数据,并用拟合或积分方法从谐振曲线中求解出准光腔的品质因数。测得双球镜开腔的固有品质因数大于8105,使该系统在工作波段可测量损耗角正切为10-5量级的低损耗介质。用该系统测出的石英、人造金刚石和蓝宝石的介电常数和损耗,与报道的结果一致,并测得4H-SiC在132.07 GHz的介电常数实部为9.598,损耗角正切为6.110-5。 相似文献
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通过仿真计算和实验研究了一种基于频率选择表面的双层改进型互补结构太赫兹带通滤波器.对四裂缝互补型电感电容式谐振单元结构进行了改进,可以在提高滤波性能的同时增加单晶石英介质衬底的厚度.利用电磁仿真技术设计并加工了中心频率为0.28 THz的带通滤波器,并利用太赫兹时域光谱仪测试了在0.1—0.6 THz范围内此滤波器的传输频谱特性,实验结果与仿真结果基本一致.结果表明,利用双层改进型互补结构可以设计出对于入射角度不敏感、带外抑制佳、边带陡峭度大、能有效抑制寄生谐振的宽带太赫兹带通滤波器,并降低了加工难度. 相似文献
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《Current Applied Physics》2010,10(2):381-385
This paper described a method for estimating the acoustic characteristics of composite materials at oblique incidence of sound waves. Composite materials are used as acoustic windows of SONAR to protect the internal sensors and electronic parts from water. In this study the composite material of glass reinforced plastic and polyurethane was used as the specimen. As the acoustic characteristics the velocities and attenuation coefficients of sound waves through the composite material were measured in the high frequency range. The insertion loss was also measured as a function of incident angle at 200 and 76 kHz, respectively. The attenuation coefficients in the low frequency range were estimated by interpolating the measured attenuation in the high frequency range with power-law form fitting. A four-medium layer model was proposed to estimate the insertion loss of composite materials at oblique incidence of sound waves in the low frequency range. The four-medium layer model well described the experimentally measured insertion loss at the high frequency range. It suggests that the insertion loss of the composite materials can be well estimated as a function of incident angle in the low frequency range. 相似文献
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Mohammed Nurul Afsar Hua Chi 《International Journal of Infrared and Millimeter Waves》1994,15(7):1161-1179
The room temperature application of sapphire as window material at higher frequencies is not feasible since its absorption coefficient increases almost linearly with increasing frequency in the millimeter wavelength region. At cryogenic temperature the absorption coefficient value decreases only by a few factors (factor of 2 to 3) in the 90 – 200 GHz region. The earlier reported temperature squared dependence (decrease) in the absorption coefficient or the loss tangent value is totally absent in our broad band continuous wave data we are reporting here (at 6.5 K, 35K, 77K and 300K) and one we reported at conferences earlier. Our results are verified by another technique. We utilize our precision millimeter wave dispersive Fourier transform spectroscopic techniques at room temperature and at cryogenic temperatures The extra high resistivity single crystal compensated silicon is no doubt the lowest loss material available at room temperature in the entire millimeter wavelength region At higher millimeter wave frequencies an extra high resistivity silicon window or an window made with extra high resistivity silicon coated with diamond film would certainly make a better candidate in the future. A single free standing synthetic diamond window seems to have higher absorption coefficient values at millimeter wavelength region at this time although it is claimed that it possesses good mechanical strength and higher thermal conductivity characteristics. It certainly does not rule out the use of diamond film on a single crystal high resistivity silicon to improve its mechanical strength and thermal conductivityThis research program was supported by the U.S. Department of Energy, Office of Fusion Research. Authors acknowledge the loan of a synthetic diamond specimen from Dr. Kevin Gray of Norton Diamond Company 相似文献
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本文的目的在于研究天然有色水晶在当作压电共振器用时它的压电振荡性能,并与无色水晶在这方面的性能上作一比较,以推断有色水晶是否可以应用到实际的控制电路振荡的工作中去。我们的工作分四方面进行:(一)有色水晶压电振荡的频率常数,(二)有色水晶压电振荡的稳定性,(三)有色水晶压电振荡的选择性及活动性,(四)有色水晶压电振荡的频率——温度系数。并且把有色水晶在用热处理方法去色后的这四方面实验结果与去色前的作一比较。实验的结果证明有色水晶是可以被激发压电振荡的,和无色水晶一样可以作控制电路振荡之用。有色水晶的Y-截法的频率常数比无色水晶的约低2%。至于两种水晶的其余两种X-截法及AT-截法的频率常数基本上无差别。热处理能使两种水晶的三种截法的压电振荡频率有增高的倾向,这效应在有色水晶中更为显著。同样,热处理对于两种水晶三种截法的压电振荡的选择性及活动性,在统计数字上看来是有益处的。最后,就以上测量的结果,推算了并讨论了有色水晶和无色水晶的若干劲度系数异同之点。 相似文献