Basic Model Of The Steady State Characteristics Of The Population Inversion Laser,

The study of lasing without inversion(LWI)is an important and active research front field in international lasing physics nowadays.The study of LWI has not only an important theoretical value,but also wide application prospects.Based on the work of the former people,we mainly studied some steady-state properties of closed V-type,A-type and Ladder-type models and presented the varying rules and features of them.Moreover,we pointed out the internal mechanisms and cause which lead to these rules and features.The study helps us further understand the steady-state properties and mechanism of production of LWI.The main results of this thesis are as follows.1.We explained the background and the significance of study of LWI and the basic principle of producing LWI,and introduced simply the current research state and the main contents for the important study subject at present.2.We introduced the ways of studying the steady-state properties of closed V-type,A-type and Ladder-type models.3.We study the rule of steady-state gain of a closed V-type atomic system and a closed A-type atomic system of lasing without inversion that follows detuning of the coherence lasers under the condition the corresponding parameters of the two atomic systems are equal by the way of numerical simulation and comparison.We find out that the curves of probe-laser gain of the two atomic systems that follow detuning of probe-laser have the similar shape,but their values are different,which has relation to the characteristics of atomic coherence and population distribution of the two atomic systems directly.In addition,we acquire that the driving laser detuning and the additional atomic coherence caused by spontaneously generated coherence can exert a great influence upon probe-laser gain.4.We study the influences of spontaneously generated coherence on population distributions of closed V-type,A-type models under the condition of certain parameters by means of numerical simulation.The result showed that when driving laser detuning is a zero value, spontaneously generated coherences make the population distributions of levels |1〉,|2〉of closed V-type and levels|2〉,|3〉of A-type approximately equal.When driving laser detuning is a nonzero value,spontaneously generated eoherences transfer part of population distributions of energy levels |1〉and |2〉to energy level |3〉as to V-type model and part of population distribution of energy level |1〉to energy levels |2〉and |3〉as to A-type model.5.We study the properties of steady-state lasing models without inversion of the closed Ladder-type under the certain parameters by the means of numerical simulation.The result shows that when the driving laser detuning is either a zero or a nonzero value,Ladder-type model has a region of gain and several gain-peak values,and its rule of probe-laser gain has the remarkable features in comparison with V-type and the A-type models,which is interrelated with its own coherences directly.In addition,Ladder-type model has stronger power in remaining the state of without inversion as to the driving laser detuning.