Quantum Coherence Induces Optical Nonlinear Transmission Characteristics Of Atoms And Quantum Dot Systems

Laser-induced quantum coherences can lead to quantum interference between the excitation pathways that control the optical response. In this way the optical properties of a medium can be dramatically modified, leading to electromagnetically induced transparency (EIT) and other related effects. EIT can not only eliminate the resonant absorption and refraction (linear susceptibility), but also enhance optical nonlinearity. Due to its promising properties, laser-induced quantum coherences are paid attention by lots of researchers. Based on EIT, we study optical bistability induced by spin-orbit coupling in the carbon-nanotube quantum dots; Based on spontaneously-generated coherence, we analyze superluminal optical solitons induced by in the V-type atomic system. The thesis consists of five chapters:In the first chapter, we introduce EIT and optical effects related with EIT such as enhancing optical nonlinearity, subluminal velocity and superluminal velocity, four-wave mixing, optical bistability and optical solitons. At the end of the part, we show the classical theory of laser interacting with media.In the second chapter, we introduce basic theory of laser interacting with media, including interacting picture, density-matrix equation, rotating-waving approximation, electric-dipole approximation and slow-varying-envelope approximation, and explain the reason and generating conditions of EIT.In the third chapter, we theoretically investigate steady-state behaviors of carbon nanotube quantum dots with spin-orbit coupling in a unidirectional ring cavity. Our results show that the spin-orbit coupling can induce optical bistability. The intensity and detuning of driving field can control the threshold of optical bistability. In addition, in existence of spin-orbit coupling, switching optical bistability to optical multistability or vice versa is realized by adjusting detuning of probe field.In the fourth chapter, we show optical solitons can be induced by the spontaneously generated coherence under the resonant coupling of probe field in a V-type atomic system. In addition, the group velocity of optical solitons could be controlled from the subluminal to the superluminal by the relative phase of the applied fields.In the fifth chapter, we summarize the thesis, and show our main conclusion. Besides, we put forward problems to be solved.