The Study Of Single Quantum Dot Laser In Microcavity

Quantum dot laser is the research hotspot of the many intercross subjects. Particularly,with the development of the nano technology, there has been considerable interest recently in the theory and experiment study of the quantum dot laser. The quantum dot laser has a lot of superior properties in contrast to the quantum-well laser and quantum wire laser. It has lower threshold current density, higher characteristic temperature , the higher gain and so on. The quantum dot laser also has a number of characteristic and physical properties, for example, surface effect, quantum tunneling, nonlinear optical effect, and so on. This improves the material properties greatly. This thesis is based on the Supervisor's National Natural Science Foundation of China "a relevant study of the new mechanism on lasing in random media "," nonlinear effects at the low light levels "and "the new mechanism study of single photon laser". The output properties of the a single quantum dot lasers in micrpcavity is investigated. The key points of this thesis are presented as follows:Summarize the properties, the fabrication, and the application of the quantum dot. The properties, the research significance and the study status quo of the quantum dot laser are also summarized.We have studied the optical and output properties of the system that consists of a single three-level quantum dot coupled to a single mode of an optical cavity. By using the master equations motion of the system, the system's properties are studied with the numerical calculation methods. It is shown that the threshold of the single quantum dot lasers is small under the function of the incoherent pumping. The steady output of the lasers is achieved soon. When the coupling strength between quantum dot and cavity is larger, the threshold is smaller and the steady output of the lasers is achieved more quickly. The coupling strength between the quantum dot and the single mode of the optical cavity is larger, the net stimulated emission is prone to a saturation curve sooner. These saturation curves get to a limit value with the increasing value of the coupling strength sooner. The net stimulated emission curves show the opposite law with the increasing value of the decay rate between the laser levels.The quantum system under investigation is a four-level quantum dot coupled a single mode of an optical microcavity. By the numerical calculation method of the quantum-optical master equations the intensity of a single quantum dot laser's evolution with the variation of the incoherent pumping rate is investigated. The results display that there is a threshold for Laser's output under the action of the incoherent pumping. The stronger of the coupling strength between the quantum dot and mode ,the smaller of threshold, and the larger peak value of laser's output. At the sufficiently high pump rates the lasing turns off to zero, because the coherence between the laser levels is destroyed. And self-quenching behavior appears.This project is supported by the National Natural Science Foundation of China (Grant No.10464002. No.60278016 & No.60768001).