J4 ›› 2010, Vol. 27 ›› Issue (4): 435-440.

• Nonlinear Optics • Previous Articles     Next Articles

Enhanced cross Kerr nonlinearity in a RY-type four-level atomic system

YAN Xiang-an1,2, LIU Han-chen1, WANG Qiu-ping1   

  1. 1. School of Science, Xi’an Polytechnic University, Xi’an 710048, China; 
    2. Key Laboratory for physical Electronics and Devices of the ministry of Education, Xi’an Jiaotong University, Xi’an 710049, China
  • Received:2009-07-27 Revised:2009-10-09 Published:2010-07-28 Online:2010-06-13

Abstract:

A theoretical program is studied on the cross Kerr nonlinearity effect in RY-type four-level atomic system. Using density-matrix equations and perturbative iterative method, the dependence of the real part of the third-order susceptibility on the variations of the additional coherent coupling field intensity and the nonradiative decay rate between the two ground states of the atoms is derived. It is found that, by decreasing the nonradiative decay rate between the two ground states and increasing the coupling field intensity, the enhanced cross Kerr nonlinearity with vanishing absorption can be obtained at two-photon Raman resonance. The research result has useful application in all-optical switch.

Key words: nonlinear optics, electromagnetically induced transparency, cross Kerr nonlinearity effect