Coherent Control Of Optical Vortex Transfer

The light-matter interaction is one of the central topics of quantum optics.The effects of atomic coherence and quantum interference are the important topics in quantum optics.Many interesting phenomena can be realized based on atomic coherence,such as electromagnetically induced transparency and coherent population trapping.The transfer of optical vortices is studied based on atomic coherent in this paper.Optical vortex is a kind of special light field which not only has spin angular momentum,but also has orbital angular momentum and unique phase singularity.The amplitude has a direction angle due to its exponential parameter,and the spatial structure presents a spiral wavefront structure.In this paper,the transfer of optical vortices and the absorption loss of the probe and control beams in different systems are studied by using the typical quantum optical method.The main research contents are as follows:1.The transfer of optical vortices is studied via double two-photon processes.In a fourlevel diamond configuration system,two strong fields are applied to form a ?-type subsystem while two probe fields are applied other with other cascade transitions.The analytical results for the intensities of the probe fields are calculated under the condition of two-photon resonance.The results show that the orbital angular momentum of on input probe beam or the control beam can be transferred to the newly generated probe beam,which is also confirmed by the numerical simulation;In addition,with the increase of the Rabi frequency of the control light,the propagation of probe beams exhibits oscillation mechanism only when the one photon detuning of two photon resonance is nonzero.Finally,we also study the methods to minimize the absorption loss and improve the optical transmission efficiency.It is found that the transmission efficiency and the absorption loss can be minimized by appropriately modifying the one-photon detuning together with the control fields Rabi frequencies.2.The transfer of optical vortices is studied based on Raman process.In a four-level cascade configuration atomic system,a pair of strong control fields are applied to produce atomic coherence,while two weak probe fields are coupled with the other two transitions.Optical vortex can be transferred from the control field to the generated probe beam based on four-wave mixing process when the control field carries optical vortices,wherein the one-photon detuning plays a key role in minimizing the losses;optical vortex can be transferred from the probe field to the probe beam based on the coherence induced by the Raman process when the control fields does not carries optical vortices.Noteworthy,it is impossible to occur when the coherence has its minimal value 0 and maximal values ±0.5.Furthermore,we have analyzed the composite probe beams when both of them carry optical vortices at the entrance.Our results display that the information of orbital angle quantum number is hidden behind the intensity distributions and corresponding phase patterns.This may find potential applications in quantum information storage.