原子在两个平行镜面间两层电介质板中的自发辐射率

利用光子的闭合轨道理论，我们研究了原子在两个平行镜面间两层电介质板（折射率分别为n1，n2）中的自发辐射率. 自发辐射率呈现出多周期的振荡结构。自发辐射率的傅立叶变换中的每一个峰和光子从原子出发到返回原子的一条闭合轨道相对应。结果表明自发辐射率和两层电介质的宽度和折射率有关。和只有一层电介质的辐射率比较，当两层电介质的折射率n1 和 n2 差别很小时, 两层电介质之间分界面的反射效应可以忽略；但是当二者的差别很大时，发射效应变得非常重要且自发辐射率中的振荡减弱。本文的结果为原子在不同电介质间的自发辐射率的研究提供了新的理解。

The Spontaneous Emission Rate of an Atom in a Two-layer Dielectric slab Between Two Parallel Mirrors

The spontaneous emission rate of an atom in a two-layer dielectric slab with refractive indices n1 and n2 between two parallel mirrors is studied using the photon closed orbit theory. The spontaneous emission rate exhibits multi-periodic oscillations. Each peak in the Fourier transformed spontaneous emission rate corresponds with one action of photon closed-orbit going away from and returning to the atom. The results showed that the spontaneous emission rate depends on the width and refractive index of the two-layer dielectric. Compared with the spontaneous emission rate of an atom in one medium, if the difference of n1 and n2 is small, the reflection effect of the dividing interface between the two-layer slab is little and can be neglected; while if the difference is big, the reflection effect of the dividing interface becomes significant and the oscillation in the spontaneous emission becomes weakened. This study provides a new understanding on the spontaneous emission rate of an atom in different dielectric slab.