Coherent control of Kerr nonlinearity via double dark resonances (DDRs)
A. Rahelia+, M. Sahraib*, A. Namdarc×, R. Sadighi-Bonabid°
+Aras International Campus, University of Tabriz, 51666 Tabriz, Iran
*Research Institute for Applied Physics, University of Tabriz, 51666 Tabriz, Iran
×Faculty of Physics, University of Tabriz, 51666 Tabriz, Iran
°Department of Physics, Sharif University of Technology Azadi Ave, Tehran, Iran
Abstract
A theoretical scheme for enhanced Kerr nonlinearity is proposed
in a four-level ladder-type
atomic system based on double dark resonances (DDRs). We solve the
relevant density matrix
equations in steady state and utilize the perturbation theory to obtain
the analytical
expressions for the third order susceptibility of the atomic system. The
influence of system
parameters on behavior of the first and third order susceptibilities is
then discussed. In
particular, it is found that an enhanced Kerr nonlinearity with reduced
linear and nonlinear
absorption is obtained around zero probe detuning under the slow light
condition through
proper adjusting the laser field intensity and frequency detuning of
driving fields. The
dressed state analysis is employed to explain the physical origin of the
obtained result. The
obtained results may be important for all-optical signal processing and
quantum information technology.