Quantum spin Hall insulators in chemically functionalized As(110) and Sb(110) films

We propose a new type of quantum spin Hall(QSH) insulator in chemically functionalized As(110) and Sb(110) film.According to first-principles calculations, we find that metallic As(110) and Sb(110) films become QSH insulators after being chemically functionalized by hydrogen(H) or halogen(Cl and Br) atoms. The energy gaps of the functionalized films range from 0.121 eV to 0.304 eV, which are sufficiently large for practical applications at room temperature. The energy gaps originate from the spin–orbit coupling(SOC). The energy gap increases linearly with the increase of the SOC strength λ/λ_0. The Z_2 invariant and the penetration depth of the edge states are also calculated and studied for the functionalized films.     

拉格朗日中值定理的推广

《高等数学》教材中的微分学基础定理，即著名的拉格朗日中值定理抄录如下：定理若函数ｆ（ｘ）在闭区间［ａ，ｂ］上连续，在开区间（ａ，ｂ）内可导，则至少存在一点ξ∈（ａ，ｂ），使得ｆ（ｂ）－ｆ（ａ）ｂ－ａ＝ｆ’（ξ），ａ＜ξ＜ｂ．本文先把这个定理推广到有限...     

微型化光纤法布里-珀罗传感器腔长一致性的控制研究

研究了光纤法布里-珀罗腔传感器的腔长一致性的控制技术.通过三维调整架组成微调装置来控制全光纤法布里-珀罗腔的腔长;结合法布里-珀罗腔的工作原理,利用光谱分析仪实时检测加工过程中法布里-珀罗腔的腔长并用装置予以修正;以热熔接的方法将毛细玻璃管与光纤加工成法布里-珀罗腔;利用超景深光学显微系统检查加工的法布里-珀罗腔的关键部位的结构,并对熔接点的牢固性进行了检测.实验结果和数据分析显示:法布里-珀罗腔的腔长得到了较好的控制及一致性,熔接部位的变形和对法布里-珀罗腔的性能的影响也很小.该工艺可用于制备全光纤法布里-珀罗腔传感器.