The Coherent Control Study Of Absorption Properties In Inhomogeneous Broadening Y-type Four-level System

The study of coherent control of optical properties and optical courses is one of the mostimportant and active research front fields in international optics nowadays. The study of coherentcontrol has not only an important theoretical value, but also wide application prospects in manyfields, such as quantum optics, nonlinear optics, quantum information and photo-communication,etc. In addition, Atomic coherence effects have multiple potential applications in many aspects.Among numerous phenomena of atom coherence,Based on the work of the former people, we studied theoretically coherent control ofabsorption properties in inhomogeneous broadening of Y-type four-level system in this paper.This paper consists of four chapters, and the main contents and results are illustrated as follows:In Chapter 1, we introduced the significance, the history and current research state ofquantum optics, coherent control, two-photon absorption and electromagnetically inducedtransparency.In Chapter 2, using the numerical result, influence of the Doppler broadening on thevacuum induced coherence (VIC) related probe field absorption is discussed. It is shown that: Ifthere is not the Doppler broadening, only when VIC is absent the electromagnetically inducedtransparency (EIT) phenomenon can occur; VIC leads to the probe field absorption varyingobviously and gain appearing; in both cases with and without VIC, the absorption curve has adouble-peaks structure which is symmetrical about the probe detuning. If there is the Dopplerbroadening, in both cases with and without VIC, EIT phenomenon always can occur; VIC stillleads to the probe field absorption varying obviously and gain appearing; regardless of that VICis present or not, the probe field absorption has following characteristics: the absorption curve nolonger has symmetry about the probe field detuning and changes gradually from thedouble-peaks structure to the single-peak structure with the Doppler broadening width (D)increasing, the probe field absorption doesn’t monotonously increase or decrease with Dincreasing, the probe field absorption when the probe and driving fields propagate along theopposite direction is smaller than that when the probe and driving fields propagate along the same directionIn Chapter 3, using the numerical result, influence of the Doppler broadening on thevacuum induced coherence (VIC) related two-photon absorption is discussed. It is shown that: (1)In the case without Doppler broadening, when VIC is absent, the absorption curve has adouble-peaks structure and the electromagnetically induced transparency (EIT) phenomenon canoccur; when VIC is present, the absorption curve has a single-peak structure and EITphenomenon doesn’t appear.（2）In the case with Doppler broadening, regardless of VIC beingpresent or not, EIT phenomenon always can occur; when VIC is absent, under the bothconditions of the propagation directions of the probe and driving fields being same and opposite,with the Doppler broadening width (D) increasing, the absorption first increases and thendecreases and the absorption curve changes gradually from a double-peaks structure to asingle-peak structure; when VIC is present, if propagation directions of the probe and drivingfields are same, with value of D increasing, the absorption first increases and then decreases andthe absorption curve changes gradually from a single-peak structure to a double-peaks structure;if propagation directions of the probe and driving fields are opposite, with value of D increasing,the absorption decreases monotonously and the absorption curve still keeps a single-peakstructure.In Chapter 4, the summary of the full paper is made, and the further research work isintroduced.