Incoherent Pump Open V-type System Of The Nonlinear Theory Of Population Inversion Laser

The study of Lasing Without Inversion (LWI) is one of the most important and the most active research field of Lasing physics internationally nowadays. There are not only important theoretic value but also wide applied prospect in the study of LWI. In this paper, we study inversionless lasing of frequency up-conversion in an open V-type system with incoherent pump. Making theoretical analysis and numerical calculation by density-matrix equations of motion, we derive the conditions for the onset of LWI and discuss the effects of the parameters of the system, the detuning of driving field and probe field on the gain, and discuss nonlinear effect in the frequency up-conversion regime. We also give stability and transient analysis. This paper consists of six chapters. In Chapter 1, we first present the significance and the principle of LWI, then introduce the research content and the progress that have been made in this field. In Chapter 2, we use an open V-type three-level system model with incoherent pump put forward by Yelin, and give a universal nonlinear analytical solution of the steady state by density-matrix equations of motion. By numerical calculation of the solution, In Chapter 3, we give nonlinear theory of the open V-type system with a monochromatic incoherent pump. The chapter comprises sections of resonant nonlinear theory and off-resonant nonlinear theory. In Section one, we analyze the mechanism of LWI gain, and study the effects of the Rabi frequency Q of the driving field, the injection rates ratio rb / r~,the exit rate r0, the decay rates ~ and rab between atomic levels, as well as 3 incoherent pump rate r on the gain without inversion, dispersion and population difference of the system. In Section two, we discuss the effects of the detuning of the driving field and the probe field on the gain. In Chapter 4,we study nonlinear theory of the open V-type system with two-color incoherent pump. In this chapter, we discuss the conditions for the onset of LWI and the stability of the system in the limit of strong driving field, and the effect of incoherent pump rate rt on the gain, dispersion and population differences. We also discuss the effect of nonlinearities and the effect of pumping rate threshold of the pumping field. In Chapter 5, we make numerical calculation, then analyze the properties of the population distribution, the gain, the coherence term and population difference, and validate the transient light amplification mechanism of this system. In Chapter 6, a summary is presented to sum up the main properties of LWI of this system.