Research On Diffraction Spectra Of Semiconductor Microstructures Based On Quantum Control

In recent years,with the development of crystal growth technology,people have been able to fabricate semiconductor quantum well materials successfully.As a new quantum coherent medium,many interesting quantum coherence and quantum interference effects are gradually extended from atomic systems to semiconductor quantum wells.Analogue to atomic structures,semiconductor quantum wells have discrete,controllable energy level structures that can be easily integrated.Due to its outstanding inherent advantages,semiconductor quantum well structures have become an excellent medium in the field of quantum information processing and have been widely used in optoelectronic devices.In this paper,we analyzed the propagation characteristics of weak probed light under the coupling of coherent standing wave field in cascaded three-level and four-level semiconductor quantum well systems.The influence of various parameters on the diffraction spectrum is investigated in detail.The main contents are as follows:(1)Firstly,the research background and preparation method of semiconductor quantum well,the principle of electromagnetic induced grating and the development of nonlinear optics are introduced.(2)The main theoretical tools used in this our word such as semi-classical theory of interaction between field and atom and electromagnetically induced transparency are briefly introduced.(3)we investigate the properties of transmission of a weak probe light in a three-level semiconductor quantum well that is coherently manipulated by a standing wave.Based on the theory of quantum coherent and of light diffraction,we can obtain the diffraction pattern of the probe light.We consider the influences of Kerr nonlinear effect on the diffraction pattern,and studies show the distribution of diffraction pattern can be controlled through choosing appropriate physical parameters of system.Kerr nonlinear effect can enhance the brightness of central pattern and improve the transmission efficiency of the incident light.(4)The interaction between the strongly coupled standing wave electromagnetic field and the cascaded four-level semiconductor quantum well is also studied.It is found that a weak probe field propagating along the direction perpendicular to the standing wave can be efficiently diffracted into the high-order direction by using electromagnetic induction.The transparent absorption and dispersion characteristics produce an induced grating that effectively diffracts light to the first order.By analyzing the effect of various parameters on the nonlinear polarizability,we can easily control the diffraction efficiency of the grating by appropriately changing the parameters of the coupling field strength and detuning and the detuning of weak probe field,so we obtained diffraction patterns of different intensity distributions.In summary,we found that Kerr nonlinearity plays a crucial role in the preparation of electromagnetically induced gratings and in controlling diffraction efficiency.A controllable diffraction pattern has potential applications in some areas,such as design of quantum diffractive optical elements,grating imaging system,precision measurement and so on.