THE EFFECT OF KERR NONLINEARITY, DOPPLER BROADENING AND SPONTANEOUS GENERATED COHERENCE ON SLOW LIGHT PROPAGATION

Zhonghua Huang, Ai-Xi Chen, Zhao-Chu Chen +1 more

In a three-level atomic system, the influences of spontaneously generated coherence on the linear absorption and the Kerr nonlinearity are investigated. Our studies show that properties of linear absorption can be dramatically affected by the effect of spontaneously generated coherence. With increase of intensities of spontaneously generated coherence, absorption inhibition will occur, and finally the atomic medium becomes transparent. Furthermore, we find that the Kerr nonlinearity can be obviously enhanced under the action of effects of spontaneously generated coherence. Comparing with traditional scheme of the electromagnetically induced transparency, absorption and Kerr nonlinearity can be controlled without need another driving field in our scheme.

Yueping Niu, Shangqing Gong

Xiang-an Yan, Liqiang Wang, Bao-yin Yin +4 more

Hazrat Ali, Ziauddin Ziauddin, Iftikhar Ahmad

The influence of Kerr nonlinearity and Doppler broadening on the slow light propagation of a dispersive atomic medium is revisited using a four-level ?-type (87Rb) atomic system under the condition of electromagnetically induced transparency (EIT). The medium exhibits an EIT process which is accompanied by normal dispersion, i.e.,?sub-luminal (slow light) pulse propagation. In the presence of Kerr nonlinearity and the Doppler broadening effect the dispersion property of the proposed atomic medium is modified, which leads to enhancement of the positive group index of the medium. The combined effect of Kerr nonlinearity and Doppler broadening on slow light propagation inside the medium is the major motivation for this work.

Hamid Reza Hamedi

Jiahua Li

We investigate the spontaneous emission spectra of a coherently driven four-level cold atomic system. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized in our system. The spectral-line enhancement and suppression can be conveniently manipulated by appropriately modulating the frequency detuning of the probe driving field. In the dressed-state picture of the probe and coupling fields, we find that this coherently-driven atomic system has three close-lying levels so that multiple spontaneously-generated coherence (SGC) arises. Our considered atomic model can be found in real atoms, such as rubidium or sodium, so a corresponding experiment can be done to observe the expected phenomena related to SGC effect, since no rigorous conditions are required.