Study On Kerr Nonlinear Coherence Control Based On Spontaneous Emission Coherence

Since the technology for laser brings about in the 1960s, the theoretical research of physics has been demonstrated on the light source. Especially quantum optics and nonlinear optics based on quantum mechanics make the great progress. The quantum coherence produced by the interaction between laser and matter plays an important role in the field of optics, then investigating the properties of nonlinearity has been the forefront and popular topics. For instance, well-informed electromagnetically induced transparent (EIT), coherent population trapping (CPT), and lasing without inversion (LWI) and so on. We all know that the quantum coherence is the phenomenon in which different energy levels correlate when light interacts with matter, which resulting from multi-channel transition of atoms. And there are a lot of ways for establishing quantum coherence on the experiments, one of which is the spontaneously induced coherence (SGC). With the spontaneously emission when the atoms jump between different levels, the quantum coherence can be generated.The work about researching the spontaneous radiation has been carried out for many years, and spontaneously generated coherence can have a significant impact on some optical effects in the field of quantum optics. But on the experiment it is difficult to build a stable spontaneously generated coherence phenomenon. In spite of this, people are still exploring the new way to simulate the physical process in the experiment. On the basis, the study of the spontaneously induced coherent made some breakthrough. Such as the change of light absorption and dispersion in medium caused by spontaneously induced coherence, the increase of the transient gain, lasing without inversion with no coherent pump, and the enhancement of third-order Kerr nonlinearity with zero absorption and so on.In the field of nonlinear optics, the research about the third-order Kerr nonlinearity is driven more attention. Because the Kerr nonlinearity has been widely used in generating single photon optical soliton and strengthening of refractive index. So that there is very important and practical meaning to obtain the enhancement of Kerr nonlinearity meanwhile inhibit absorption. The main work of this article is to discuss the effects which relative phase makes on the Kerr nonlinearity with considering the presence of the spontaneously induced coherence. The thesis mainly is divided into four parts:1. The first part is a general overview of physics phenomenons. Making detailed theoretical explanation for quantum coherence, spontaneously induced coherence, Kerr nonlinearity, and formation of the basis for our main work.2. The second is mainly introducing the research methods of this paper:The semi-classical theory of interaction between light and matter. Especially understanding the calculation methods of quantum mechanics density matrix method and Probability amplitude equation.3. The third part which is the main work of this article is investigating the influences of relative phase has on the third Kerr nonlinearity and eventually finding the Kerr nonlinearity can be enhanced with zero absorption when we control the phase.4. The finally is the full text of the summary and expectation to nonlinear optics and quantum optics..