The effect of giant Kerr nonlinearity on group velocity in a six-level inverted-Y atomic system

Abstract

We propose an analytical model to study the effect of giant Kerr nonlinearity on group velocity of probe light in a six-level inverted-Y atomic system under electromagnetically induced transparency (EIT). In this scheme, a nonlinearity of the medium is enhanced greatly around in three spectral regions corresponding to transparent windows. As a consequence, such a giant Kerr nonlinearity of the medium changes significantly group index for probe light which can obstruct light slowdown. Moreover, this model shows also that the probe propagation can switch between subluminal and superluminal modes in three EIT windows by adjusting the parameters of the signal and coupling fields. Such analytical model is not only convenient for considering the influence of laser parameters on group velocity but is also easy used to fit the experimental results.

An analytical model for cross-Kerr nonlinearity in a four-level N-type atomic system with Doppler broadening

“…In this section, we apply the analytical model to 87 Rb atom, where |1 and |2 are two hyperfine levels of the ground state |1 = |5S 1/2 , F = 1 and |2 = |5S 1/2 , F = 2 , while |3 and |4 are two hyperfine levels of the excited state |3 = |5P 3/2 , F = 2 and |4 = |5P 3/2 , F = 3 . The atomic parameters are [30,33] 2(a). We can see that when the coupling field is absent, i.e., Ω c = 0, the cross-Kerr nonlinear coefficient is equal to zero (see the dotted line).…”

“…[27,28] In addition, the influences of cross-Kerr nonlinearity on light propagation in transparency media were also performed. [29][30][31][32] Although the cross-Kerr nonlinear effect has been implemented in an ultra-cold four-level N-type atomic system, most applications of Kerr nonlinearity often use hot atomic gas media that is always governed by the Doppler effect. Therefore, the study of the Kerr nonlinear effect in the presence of Doppler broadening is necessary to be applied to photonic devices working under different temperature conditions.…”

Electromagnetically induced grating via Kerr nonlinearity and spontaneously generated coherence in a Doppler broadened four-level N-type atomic system

“…An enhanced Kerr field has been observed experimentally in Bose condensate sodium atom [22,23]. The slowing down of light has been achieved in the presence of giant Kerr nonlinearity in an inverted Y-type atomic medium [24,25]. The enhancement of cross and self-Kerr nonlinearity in the Doppler broadened medium has been investigated [26,27].…”

Switching between slow light and fast light by static magnetic field in a degenerate four-level atomic system at room temperature

“…On this basis, extremely slow or superluminal light pulses were obtained in the EIT [7][8][9] or EIA [10][11][12] regime, respectively. In particular, some recent studies have shown that it is possible to switch between EIT and EIA modes [13] and thus can switch between fast light and slow light by external fields such as using microwave field [14], standing-wave field [15], Kerr field [16][17][18], coherent pump field [19,20], incoherent pump field [21][22][23], static magnetic field [24,25], or using other coherence effects such as spontaneously generated coherence [22,23,[26][27][28][29] and the phase of applied laser fields [30,31] and so on.…”