Spontaneous Radiative Properties Of Atoms In Photonic Crystal Research

In 1987 ,a remarkable step was made by Yablonovitch, who pointed out the possibility of the realization of photonic bandgaps,localized defect modes,and their applications to various optoelectronic devices, and by John who dicussed the strong localization of electromagnetic waves in disordered photonic crystals and also predicted many interesting quantum optical phenomena that can be realized in photonic crystals such as the bound state of photons and non-exponential decay of spontaneous emission. Since 1987,many researchers have been engaged in the realization of photonic bandgaps,localized defect modes,and other optical properties peculiar to the photonic crystals.Because photonic crystals are artificial crystals,it is our studing issue to design and fabricate the photonic crystals.Many accurate numerical calculations could be performed thanks to the development of computing facilities.These calculations were really useful for the design of the photonic crystal structures. As for the experiment studies, many researchers in various fields have been collaborating to make new photonic crystals and measure their properties.The method that is used in controling spontaneous emission of a two-level or three-level atom in this paper. Such control can be realized in case where a atom interact with photonic band gap matericals when the atom is placed in photonic crystals whose density of modes is dramatically different from that of free space vacuum.It was known that control could be achieved by varying the frequency(which leads to the changes of the relative position of the upper levels from the forbidden gap)or by varying the photonic density of modes(DOS) or by varying the intial atomic state.In this paper,starting from the fundament theories for the description of the spontaneous emission, the property of spontaneous emission of a two-level atom embedded in photonic crystals was first investigated. Spontaneous emission can be totally suppressed or strongly enhanced depending on the relative position of the resonant frequency from the edge of the photonic band gap and the photonic mode density.Several novel phenomena can be obtained.the spontaneous emission displays an oscillatory behavior,classical light localization, photon-atom bound state,nonzero steady-state population and anomalously large vacuum Rabi splitting.And localized mode associated with a defect site in an otherwise perfect photonic crystals,acts as a high-Q micro-cavity. They are useful for filters,single-mode lasers.Meanwhile,we take further researchs into the property of spontaneous emission of a two-level atom embedded in photonic crystals,one-dimensional comblike photonic crystals for example. The properties of spontaneous emission depend notonly on the relative position of the resonant frequency from the edge of the photonic band gap and the photonic mode density but also on the relative distance of the atomic space position from the sidebrand.And we study other property of spontaneous emission.In addition, the control of spontaneous emission of a three-level atom embedded in photonic crystals was investigated in this paper,because the model of two-level atom is siple.As it shows,the properties of spontaneous emission depend not only on the relative position of the resonant frequency from the edge of the photonic band gap and the photonic mode density but also on the intial atomic state.