Optical Properties Of The Surface Of Chiral Atom Medium

Coherent preparation by laser light of quantum states of atoms and molecules can lead to quantum interference in the amplitudes of optical transitions.In this way the optical properties of a medium can be significantly modified,leading to electromagnetically induced transparency and related effects,which have placed gas-phase systems at the center of recent advances in the development of media with radically new optical properties.The five-level atomic system,which is affected by the probe field and the control field,is called chiral atomic medium because of that the coherent coupling between the magnetic dipole transition and the electric dipole transition leads to electromagnetically induced chirality.In this thesis,we mainly study the Kerr/Faraday polarization effect of five-level chiral atomic medium.When the control field applied on the atomic medium changes,the optical properties of the atomic medium will be varied with it,so as to achieve the effect of controlling Kerr/Faraday polarization.The specific work is as follows:Firstly,the recent researches on the properties of chiral atomic medium and Kerr/Faraday effect are summarized,and the significance of studying chiral atomic medium is stated.Then the level structure of chiral atomic medium is described in detail.At the same time,because the optical parameters of the medium can be adjusted by the control field,the generalized expressions of the permittivity,the permeability,the chirality coefficient and the refractive index of the chiral atomic medium with magneto-electric cross coupling are derived.Finally,the advantages and application scenarios of chiral atomic medium compared with chiral media are given.In this thesis,the reflection coefficient and transmission coefficient of light incident from vacuum to the interface of chiral atomic medium are derived.According to the calculation results,the expressions of polarization conversion rate and phase difference of reflection wave are obtained.Through these two properties,the Kerr polarization effect of reflection wave at the interface is studied.The results show that many different polarization phenomena in regard to S-polarized incident wave can be obtained by changing the amplitude and phase of the control field.Regarding the chiral atomic medium,due to the high detuning,the cross coupling effect is weakened,and the low detuning is easier to achieve the full polarization conversion.When the real part symbol of the refractive index of the left and right circular polarization wave and the amplitude of the control field changes,the polarization conversion results are different.Under the condition of high detuning and high amplitude,the incident angle to achieve complete polarization conversion can be altered by changing the phase of the control field.Under the condition of low detuning,the amplitude affects the result of polarization conversion,when the amplitude is high,the complete polarization conversion is not sensitive to the incident angle,when the amplitude is low,the P-component with large value can be obtained.Next,the Faraday polarization effect of transmission wave is analyzed.In this thesis,the Faraday effect of the finite thickness chiral atomic medium is studied.Firstly,the transmission matrix and reflection matrix of the finite thickness chiral atomic medium are obtained by the transfer matrix method.According to the definition of Faraday angle,the relational expression of Faraday angle and parameters of the chiral atomic medium is obtained.By changing the amplitude and phase of the control field,the Faraday effect can be effectively controlled and the best Faraday angle of 90°can be achieved.When the extinction coefficient is negative,the Faraday angle of vertical incidence can be greatly improved,and the incident wave can be amplified.The Faraday effect can also be affected by changing the thickness of the chiral atomic medium.When the thickness of the chiral atomic medium is large enough,the Faraday effect has a certain periodicity.The above discussed method can also be used to study the Kerr effect of the finite thickness chiral atomic medium.