The Fluorescence Spectrum Of Cascade Three-level Atom In Two-Mode Cavity Field

When the atoms is placed in the vacuum, due to the influence of vacuum fluctu-ation, decaying and fluorescence radiation will occur between the two levels of atoms that meeting the transition selection rule. When the intrinsic transition frequency between the two levels that satisfying the rule is equal to the frequency of the light field, atoms in the light field will radiate resonance fluorescence. The spectra of res-onance fluorescence are impacted by the properties of coupling light field such as quantum and statistics, and optical cavity parameters such as cavity detuning and damping ratio, thus producing divers spectra. If not, atoms will also radiate fluo-rescence, but the spectra structure present diversity, satisfying a certain regularity. In this case, main reasons for the diversity of the spectra are the effects of optical cavity parameters and the properties in quantum and statistics of the driving light field. After the quantization of the light, we know that it consists of photons with creation a(?) and annihilation operator a. Light field possesses quantum states such as coherent state, squeezed state, entanglement state, but also statistical properties such as random fluctuations of photons, energy and intensity. Thus in most cases, the application of quantum theory about the interaction between light and matter is necessary for the research of atomic fluorescence.In this paper features of the fluorescence spectra coming from cascade three-level atoms in the optical cavity are investigated. Firstly, we consider that the driving light field is classical field. If the detuning of the intrinsic transition frequency between the two levels of the cascade three-level atoms differs from the frequency of the driving light field, fluorescence spectra in five-peaks structure or seven-peaks will be radiated from the atoms. Then, discuss the fluorescence spectrum properties of cascade three level atoms interacting with the quantum cavity field that its initial state is the coherent states. Specifically discussed the relations of fluorescence intensity and spectral distribution between cascade three level atoms and optical cavity parameters, namely, light field damping k1and k2,and the optical cavity detuning△c1and△c2.The studies indicate that the atomic fluorescence spectrum is different from the classical optical field, the fluorescence spectra are affected by the optical cavity parameters and the properties in quantum and statistics of the light field. There are two aspects. One is that the intensity of the fluorescence coming from cascade three-level atoms will be increased or decreased due to the role of quantum light field. Another is that with the variation of optical cavity parameters, changes of spikes of the cascade three level atoms fluorescence spectra will be varied.