Kerr nonlinearity based on wavelength mismatching and quantum interference in microwave driven Y-type atomic system

Abstract

A theoretical study is carried out for investigating the first- and third-order susceptibilities in a four-level Y-type atomic system. In this work, we present the wavelength mismatching effect on linear and nonlinear susceptibilities by considering three different wavelength regimes, i.e., near matching, partial mismatching and complete mismatching of wavelengths. Thereafter, in the case of near matching regime, the two upper excited states are coupled by a microwave field that makes a closed-loop of transitions. Therefore, a relative phase factor among fields becomes responsible for significant modification of susceptibilities of atomic medium. An enhanced Kerr nonlinearity with smaller linear absorption is obtained under specific parametric conditions. We attribute the enhanced Kerr nonlinearity to the quantum interference between the transition pathways.