Research On Electromagnetically Induced Transparency And Related Phenomena Based On Vortex Beam

Since the concept of "quantum" was proposed,there have been many strange phenomena about the interaction of light and matter.As an important aspect of quantum physics research process,quantum coherence phenomenon still has very important research significance until today.In recent years,tremendous progress has been made in the generation and detection of vortex beam,and its control of quantum coherence effects has potential applications in high-capacity optical information storage and continuously variable quantum technology.In this thesis,quantum coherence phenomena such as electromagnetically induced transparency and four-wave mixing are studied by means of the basic theory of quantum optics and vortex light.Firstly,the research status and research progress of electromagnetically induced transparency and other coherent phenomena based on vortex light at home and abroad are briefly introduced.Then,the basic concept of vortex light,the basic theory and related knowledge of the interaction between light and matter are introduced.Finally,the basic tools of quantum optics are used to make a theoretical study of quantum coherence effects in two different systems.The main contents are:(1)We present a scheme for realizing the manipulation of probe absorption spectrum by adjusting the orbital angular momentum(OAM)carried by the optical vortex beams and the frequency detunings in a four-level cascaded atomic system.We start by establishing a theoretical model and possible experimental setup for achieving vortex induced transparency and vortex induced absorption,and we adopt density-matrix method to obtain the complex susceptibility of the non-vortex probe beam.We then consider the influence of OAM on the absorption spectrum under resonance and non-resonance conditions.The numerical simulation results show that the absorption peak appears at the vortex core while the absorption losses decrease or disappear on the doughnut-shaped structure away from the vortex core in the resonance case,and the center is translucent or transparent while the absorption losses appear at the circular track away from the center on the non-resonance.These phenomena originate from the quantum interference and the unique properties of vortex light beams.(2)We investigate in detail the azimuthal and radial modulation of double-four-wave mixing(double-FWM)by use of two higher-order Laguerre-Gaussian(LG)beams in a Landau quantized graphene ensemble.A pair of weak probe pulses in the graphene ensemble interacts with two LG beams and thus two vortex FWM fields with the opposite vorticity are subsequently generated.