Theoretical And Experimental Study On N Four Level Electromagnetically Induced Grating

In recent years,the atomic coherence effects have aroused widespread concern,using a standing wave to replace the traveling wave of electromagnetically induced transparency(EIT),an electromagnetically induced grating(EIG)is formed.The traditional diffraction grating is limited by the manufacturing and processing technology,so that it can not adjust the grating constant in time,however the electromagnetically induced grating can through real-time modulation signal and coupling light then to change each property of the grating in real-time,and can real-time modulation probe photometric diffracted,thus overcoming the limitations of ordinary grating.So it has great application prospect in all-optical switches and all-optical network control.Therefore,on the one hand,the preparation of the ultra cold environment requires a very complex process,which limits its application in a wider range of applications.The realization of the system and thermal atom than the cold atomic system is much easier,the first-order diffraction efficiency of N type electromagnetically induced grating in hot atoms is theoretically investigated.On the other hand,the beam shaping experiment is carried out for the divergence of the elliptical shape of the semiconductor laser beam,which paves the way for the next electromagnetically induced grating experiment.The main work of this paper is:1,Through the numerical simulation method to adjust the parameters affecting the detection level of the diffraction efficiency of probe light,thermal and cold atomic system makes the first-order diffraction efficiency of a probe respectively 31% and 34%,which means the only thermal atomic system with 3% lower,but the thermal atomic system preparation easier than cold atomic system,which makes the electromagnetically induced grating effect of thermal atomic system has more advantages in practical application,then has a potential application prospect in optoelectronic device.2,The three beam shaping schemes of anamorphic prism pair,cylindrical mirror and optical fiber are used to shape the beam of semiconductor laser.The three shaping schemes are compared and analyzed,and an ideal scheme of fiber shaping is selected,which will pave the way for the next electromagnetic induction grating experiment.In this paper,innovative work is available:A,Before the research is basically to study cold atomic system,in this paper through numerical simulation method to explore the thermal atomic system,and compares the cold atomic and thermal atomic system of N type four level electromagnet ically induced grating quality,provides the theory basis for the experiment.