Properties Of The Temporal Optical Solitons In The Semiconductor Quantum Dots Electro-magnetically Induced Transparency Medium

Optical solitons are light pulse that can keep unchanged waveform,amplitude and velocity when the light propagates in the medium.So the optical soliton communication system is expected to become one of the effective schemes for realizing high-speed,high-capacity and long-distance all-optical communication.In general,the optical soliton can be divided into the spatial and temporal optical soliton.The former is formed when the nonlinearity effect of nonlinear medium and the beam diffraction balance each others;the latter is formed when the nonlinearity effect compensates for the dispersion effect.Based on quantum coherence and interference effects,the electromagnetically induced transparency(EIT)medium can provide an ideal propagation place for the optical soliton.It is mainly because EIT medium can stimulate strong nonlinearity effect by means of weak optical field and eliminate the absorption of the medium.Up to now,the studies on temporal optical soliton and spatial optical soliton in the ultracold atomic EIT medium are becoming more and more mature.However,due to the defects of the ultracold atomic,such as low temperature,thin,and difficult to be precisely controlled,it is difficult to miniaturize quantum device in the specific application.The quantum dots,which is known as“artificial atoms”,is becoming one of EIT ideal medium.It has not only discrete energy level similar to ultracold atomic,but also large electric dipole moments,long decoherence time,easy integrating,and other advantages.In addition,the increasingly sophisticated semiconductor process and manufacturing technology provide also broad application prospects for the quantum dots in semiconductor devices.Therefore,the studies on the properties of the temporal optical solitonin the semiconductor quantum dots EIT medium are of theoretical and practical significance.In this thesis,we study the properties of the temporal optical soliton in the semiconductor single quantum dot and the triple quantum dots molecular system.The main structure of this thesis is the followings.First,the preparation and the application prospect of the ordinary and with EIT effect semiconductor quantum dots are overviewed.Then,the basic theory and the method of the studies on the temporal optical soliton are briefly introduced.Finally,we give a briefly summary of the main results in this thesis.The actual semiconductor quantum dots,which is affected by EIT effect,may appear the phonon-assisted transition effect.So,we consider the phonon-assisted transition effect based on the current experimental conditions.Then,a annularfour-level semiconductor single quantum dot EIT model,which formed by the inaction between a weak probe light,two strong couple light and semiconductor single quantum dot,is proposed.Subsequently,we analytically study the properties of the temporal optical soliton in this system.It is found when the nonlinearity effect of the system can balanced with the dispersion effect,the temporal optical soliton can be generated and propagated steadily.Finally,the numerical calculation shows that the amplitude,the width and the group velocity of the temporal optical soliton can be controlled by the strength of the phonon-assisted transition.In addition,because the group velocity of the soliton is much smaller than the velocity of the light,and when the strength of the phonon-assisted transition increases,light stagnation may appear so that it is good for realizing optical storage.It provides a certain reference value for semiconductor quantum devices to realize optical storage.In general,the quantum dots molecule is made up of some single quantum dots by a certain coupling effect.So that in the quantum dots molecule systems,the coupling strength will have some influence on the optical properties of linear and nonlinear.Therefore,we propose a the four-level semiconductor quantum dots molecule EIT model,which is formed by the interaction between a weak probe light and triple quantum dot molecule.Then,the effects of interdot tunneling coupling on linear absorption and the nonlinear properties of the temporal soliton in triple quantum dots molecule are studied.The results showed that,for the linear case,the width of tunneling induced transparency window can be effectively controlled by appropriately adjusting the interdot tunneling coupling strength.Meanwhile,the strength of tunneling coupling can be used to realize conversion of tunneling transparency single-window and double-window.For the nonlinear case,it is found that the temporal soliton can be formed by a weak light in the semiconductor triple quantum dots molecule.And the type of temporal optical soliton(which is whether bright or dark optical soliton)can be controlled by adjusting the interdot tunneling strength.Finally,the research results of the temporal optical soliton in semiconductor quantum dot EIT media are summarized.Then,we prospect the follow-up work of nonlinear optical in the semiconductor quantum dot EIT medium.