Six—Parameter Exponential—Type Potential and the Identity for the Exponential—Type Potentials

We propose a six-parameter exponential-type potential (SPEP),which has been shown to be a shapeinvariant potential with a translation of parameters.For this reducible potential,the exact energy levels are obtained by using the supersymmetric shape invariance technique.Choosing appropriate parameters,four classes of exponential-type potentials and their exact energy spectra are reduced from the SPEP and a general energy level formula,respectively.Each class shows the identity except for the different definitions of parameters.     

Long—Range Effects on the Pyroelectric Coefficient of Ferroelectric Superlattice

Long-range effects on the pyroelectric coefficient of a ferroelectric superlattice consisting of two different ferroelectric materials are investigated based on the transverse Ising model.The effects of the interfacial coupling and the thickness of one period on the pyroelectric coefficient of the ferroelectric superlattics are studied by taking into account the long-range interaction.It is found that with the increase of the strength of the long-range interaction,the pyroelectric coefficient decreases when the temperature is lower than the phase transition temperature;the mumber of the pyroelectric peaks decreases gradually and the phase transition temperature increases,It is also found that with the decrease of the interfacial coupling and the thickness of one period.the phase transition temperature and the number of the pyroelectric peaks decrease.     

Transparency and Strong Gain Without Population Inversion in Photonic Bandgap Crystals

Without using the weak-field approximation,we investigate the transient properties of a Λ-type atom with one transition near resonant with a photonic bandgap edge.Whatever the initial state of the atom is,the atom can become transparent to a probe field,and strong gain without population inversion is also possible if the atom has been pre-excited.The defect mode formed by atomic doping can have a strong effect on the absorption properties of the atom.     

A Pseudospectral Time—Domain Algorithm for Calculating the Band Structure of a Two—Dimensional Photonic Crystal

A pseudospectral time-domain (PSTD) method is developed for calculating the band structure of a two-dimensional photonic crystal.Maxwell‘s equations are rewritten in terms of period fields by using the Bloch theorem.Instead of spatial finite differences,the fast Fourier transform is used to calculate the spatial derivatives.To reach a similar accuracy,fewer sample points are required in the present PSTD method as compared to the conventional finite-difference time-domain methods.Our numerical simulation shows that the present PSTD method is an efficient and accurate method for calculating the band structure of a photonic crystal.     

索尼LCX029CRT液晶显示器纯位相调制特性的研究

为了研究索尼LCX029CRT液晶显示器纯位相调制特性,设计了索尼LCX029CRT液晶显示器的驱动电路,并搭建了测试光路对其纯位相调制特性进行了研究,同时对光路进行了理论分析。实验获得一组移动的干涉条纹,实验测试研究结果表明索尼LCX029CRT液晶显示器具有π／2的相位调制特性。     

化学发光法大气氮氧化物浓度自动分析仪中光信号探测模块温控系统设计

化学发光法是测量低浓度的大气氮氧化物含量的有效方法,可用于24h连续自动分析的大气环境监测系统。然而该方法需要高温转换室、高压臭氧发生模块、高温反应室等模块,使得仪器内的环境分布极为复杂,仪器在长时间运行后容易出现灵敏度下降、信噪比降低等现象。针对上述现象,设计了用于仪器的光信号探测模块的温度控制系统。该温控系统基于PID控制原理,通过AVR单片机ATMEGAl6对半导体制冷片（Ther—mo—ElectricCooling,TEC）的闭环控制来实现温度的精密控制。实验结果表明,该系统可以使光信号探测模块的温度控制在5℃±0．1℃,光电倍增管的暗噪声从25℃时的363个／s下降到5℃时的8个／s光子数,噪声波动标准差也从22降到3,能够很好地满足系统对信号探测稳定性的要求。     

关于电学基础课程物理量的量纲与单位的讨论

本文从“量”的等式观点出发,阐述了电学基础课程相关物理量的量纲与单位问题,包括将已知量代入方程的方法,导出量纲与导出单位,标准函数的量纲等。特别指出,单位冲激函数的量纲是倒时间量纲,单位阶跃特性s(t)与单位冲激特性h(t)都是响应与激励量值的某种比值,它们都不具有电压或电流的量纲,不是普通意义上的响应。唯此,卷积积分公式的量纲才能平衡。本文目的是激发广大教师在课程教学中努力探索量纲问题的积极性。