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基于基础教育改革对教师专业化发展的呼唤,面向日常教学生活的教师教育研究,在观念上应该突出日常教学实践、行动研究和教师专业发展之间的联系,开展融于日常实践的教育研究、过一种有理论的教学生活、追求理论与实践统一的发展;在研究领域上应该广及学科教学直至师生的真实发展;在研究途径上着重基于体验的反思与批判、理论引领实践的教研、面向问题的交流与研讨等方面. 相似文献
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DMD光栅的衍射特性及其在可调谐激光中的应用 总被引:1,自引:0,他引:1
相比较于液晶空间光调制器,数字微镜晶片(DMD)具有开关速度快、显示精度高、偏振不相关、衍射效率高和宽带调制等优势。研究利用DMD的衍射效应作为波长选择器,将其应用于可调谐光纤激光器中,理论推导这种二维DMD光栅的衍射效率与入射光角度,像素间距等物理量之间的定量关系,重点讨论了两种不同像素间距的0.7″和0.55″DMD在单像素因子和多像素干涉共同作用下的衍射级数和强度分布。研究结果表明:0.7″DMD在光强不显著为零且满足实验约束条件下,允许出现4个干涉极大值,但由于极大值位置均远离闪耀条件,因此光强相对较弱。0.55″DMD仅出现1个干涉极大值,且接近闪耀条件,因此光强和效率均明显高于0.7″DMD的情况。由此可见,在可调谐光纤激光器中,利用0.55″DMD光栅作为波长选择器更有利于减小衍射损耗,提高系统稳定性。 相似文献
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Light propagation properties of two-dimensional photonic crystal channel filters with elliptical micro-cavities
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Light propagation through a channel filter based on two-dimensional photonic crystals with elliptical-rod defects is studied by the finite-difference time-domain method. Shape alteration of the defects from the usual circle to an ellipse offers a powerful approach to engineer the resonant frequency of channel filters. It is found that the resonant frequency can be flexibly adjusted by just changing the orientation angle of the elliptical defects. The sensitivity of the resonant wavelength to the alteration of the oval rods' shape is also studied. This kind of multi-channel filter is very suitable for systems requiring a large number of output channel filters. 相似文献
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本文研究了准晶光子晶体的局域态密度和全态密度.结果表明,准晶光子晶体的局域态密度分布具有和准晶光子晶体完全相同的对称性,带隙内光子晶体中的态密度很小,不同的准晶光子晶体的局域态密度随介电材料的占空比的变化是不同的,这对构造准晶光子晶体是非常重要的.准晶光子晶体的全态密度所显示的带隙和透过率显示的带隙的一致性表明准晶光子晶体在某种程度上是各向同性的. 相似文献
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基于基础教育改革对教师专业化发展的呼唤,面向日常教学生活的教师教育研究,在观念上应该突出日常教学实践、行动研究和教师专业发展之间的联系,开展融于日常实践的教育研究、过一种有理论的教学生活、追求理论与实践统一的发展;在研究领域上应该广及学科教学直至师生的真实发展;在研究途径上着重基于体验的反思与批判、理论引领实践的教研、面向问题的交流与研讨等方面。 相似文献
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Theoretical study of enhancement and suppression of the fluorescent spectra of dye molecules in a photonic crystal with a pseudogap
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We have investigated the analytical forms of the photonic density of states (DOS) in a photonic crystal in the interested frequency regime according to the rule of state conservation in a photonic crystal with pseudogaps, which states that, if a valley of the DOS appears in some range of frequencies, it must be compensated for by increasing over some other ranges. By using a model DOS with a state-conservative photonic pseudogap, we have also investigated the enhancement and suppression of spontaneous emission of two-level atoms with different frequency positions and widths of emission spectra in a state-conservative electromagnetic reservoir; and the DOS-induced suppression, enhancement, narrowing and redshifting or blueshifting of spontaneous emission spectra are naturally obtained. 相似文献
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Controlling the self-collimation characteristics of a near-infrared two-dimensional metallic photonic crystal
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Self-collimation characteristics of the two-dimensional square-lattice photonic crystal(PC) consisting of metal rods immersed in silicon are studied by the finite-difference time-domain method.The Drude dispersion model is adopted to describe the metal rod,and the self-collimation behaviours of the near-infrared light through the PC are studied.The frequency region and the tolerance of incident angle for the self-collimation behaviour can be controlled by changing the shape of the metal rods. 相似文献
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