Control And Application Of Spontaneous Emission And Stimulated Radiation Properties Of An Atom In Optical Micro-device

Spontaneous emission has turned out to be one of the most severe limiting factors for the storage and processing of quantum information,high frequency lasers, high precision measurement,and many other novel discoveries in modern quantum optics.An important interest of modern quantum optics is to devise ways to modify and control the spontaneous emission,one can modify the environment surrounding the given atom so that the atom interacts with a modified set of vacuum modes and there are different densities of modes to enhance or suppress the spontaneous emission rate.On the other hand,an optical laser containing only a single active atom has been realized with the development of atom traps technology, one can control and study the characteristics of a single atom.In complex environments(photonic crystals or microcavity),the atom driven by external laser fields has attracted a lot of interest.We investigate the influence of the environments on the decay behaviors of the spontaneous emission.Firstly,we study the spontaneous decay rate of a quadrupole placed between two parallel plates(one or both the plates have infinite permeability). In the cases of two conducting plates or two permeable plates,the fluctuations exhibit a symmetric profile with respect to the central plane of the plates.While in the case of a conducting plate and a permeable plate,the oscillations lack the symmetry. The relative spontaneous decay rate of the quadrupole exhibits oscillation with the position of the atom;For further understanding the control of an atomic spontaneous emission by the variation of the environment the atom is placed in, we discuss the spontaneous decay rate of a two-level atom embedded in a planar cavity with perfect conducting cladding.We analyze the effect of lateral shift on spontaneous decay.It is found that the spontaneous decay can be enhanced or suppressed owing to the positive and negative lateral shift at the interfaces between the air and the dielectric layers;Considering the knowledge of spontaneous emission characteristics outside the planar optical waveguides is very important for the atom trapped outside the planar optical waveguides,we study a coupling behavior,which transfers energy of spontaneous emission from the atom embedded in free space into a symmetrical metal-cladding optical waveguide.The couple efficiencies into normal guided modes and surface guided modes are shown respectively.By properly adjusting the thickness of the top metal film,the thickness of the middle layer of the waveguide and the atomic position,the coupling efficiency to normal guided mode can reach 90%.We also investigate the characteristics of the system including a atom driven by external fields in complex environments.Firstly,we discuss the Kerr nonlinearity of a V configuration three-level atom interacted with a single-mode cavity as well as one of its excited states coupled to its ground state by a strong laser field but the other one of its excited states is probed by a weaker probe beam.The influences of the cavity field frequency,the cavity field-atom coupling constants and the atomic decay constants on the linear and Kerr nonlinear susceptibilities are presented.The Kerr nonlinearity can be enhanced,accompanied by relatively vanishing linear and nonlinear absorption,which is the common result from the Purcell effect and the cavity-induced quantum interference;We also study the squeezing and spectral properties of a coherently pumped a two-level atom laser in a photonic crystal microcavity.The squeezing of the single mode cavity field is influenced by the driving field Rabi frequency,the cavity-mode frequency detuning from that of a coherent external field and the cavity decay rate.The spectral linewidth narrowing is due to the common effect of squeezing and the radiation reservoir of the photonic band gap.