| Spontaneous emission is generally recognized as one of the main reasons that lead to de coherence inquantum ensemble. But under certain conditions, it is possible to create quantum coherence effect frommultiple spontaneous emission channels thereby to change the optical properties of the medium. This isSpontaneously Generated Coherence（SGC）. As a kind of very important quantum coherence effects, aseries of interesting physical phenomena can be generated by spontaneously generated coherence such asCoherent Population Trapping, Lasing Without Inversion, Electromagnetically Induced Transparency, KerrEffect, Slow Light and so on.In the early, the studies of quantum optical phenomena based on spontaneously generatedcoherence are all almost in the atomic system. It is very difficult to meet the needs ofapproaching degenerate levels with the occurrence of spontaneously generated coherence inthe real atomic system. Although some people have put forward to a series of ways to evadethe harsh conditions from generating spontaneously generated coherence effects, all thesedaring ideals are based on the theory, which haven’t been verified experimentally. So theseideas, which are very difficult to reproduce, have just remained at the theoretical constructs.However, with the development of semiconductor technology and the continuousimprovement of doped technology in semiconductor material, a new type of semiconductorquantum well media, also referred to artificial atoms, has become a good carrier to study theoptical properties of material in. For the specifications of quantum well can be set artificiallyaccording to the needs of the practical problems, the study of spontaneously generatedcoherence based on semiconductor quantum well, which is under the use of the nature ofsemiconductor quantum well, is very meaningful. Compared with atomic system, there are alot of inherent advantages in semiconductor quantum and the results can be easily andperfectly got in the experiment.The influence of spontaneously generated coherence on the transmission of weak opticfield based on semiconductor quantum well is respectively discussed with the method ofprobability amplitude and density matrix. This thesis is totally divided into four chapters, asfollows:(1) The background knowledge from the research questions is overviewed.(2) The semi-classical theory of interaction between light and matter and relatedfundamental theoretical tool has been presented.(3) Properties of transmission of a weak pulsed light in an asymmetric semiconductorquantum well are investigated with the method of probability amplitude. Under the condition of same physical parameters, the absorption of pulsed light in media can besignificantly restrained with the enhancement of SGC. When the intensity of SGC isclose to the maximum, the media will become transparent. In addition, with theenhancement of SGC, nonlinearity of the system significantly is enhanced and thedispersion curve becomes steeper and the maximum of dispersion also enters thetransparent window.(4) An asymmetric semiconductor double quantum well coupled with a probe field and astrong coupling field is investigated with the method of density matrix. Under thecertain frequency of coupling field and decay rate and detuning, we researchabsorption and chromatic dispersion of pulsed light via changing the cross couplingterm resulted from the spontaneously generated coherence effect. With theenhancement of SGC, transparent window of system will continue to be narrow. Atthe same time, dispersion curve will become steeper. There may appear slow lighteffect in this system and the nonlinear effect is effectively enhanced.Quantum process of interaction of light and matter can be changed by spontaneouslygenerated coherence effect. The above study based on semiconductor quantum well materialwill help to deepen the understanding of the physical processes and improve thecharacteristics of the quantum system. It is a good guide to theoretical research and practicalapplication. |
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