Λ型三能级原子系统中Raman跃迁增强的Kerr非线性效应

Enhanced Kerr nonlinear effect of Raman transition in a Λ-type three-level atomic system

在理论上研究了Λ型三能级原子系统Raman跃迁中的线性和非线性极化率.研究表明:Raman跃迁中,如果原子完全被抽运到与控制光作用的基态时,将导致介质对探针光的线性极化率为零,而三阶非线性极化率不为零.通过减小原子两基态间的无辐射衰减速率γ12,可以极大地增强交叉Kerr非线性效应.

We report a theoretical study of linear and nonlinear susceptibilities of Raman transition in a Λ-type three-level atomic system. In the Raman transition, if the population of atoms is all prepared in the ground state which interacts with the control light, the linear susceptibility equals zero, while the third-order nonlinear susceptibility does not equal zero. By decreasing the nonradiative decay rate γ_12 between the two ground states of the atoms, the Kerr nonlinear refractive index for cross-phase modulation can be significantly enhanced.