We investigate the linear and nonlinear dispersion and absorption properties of a weak probe
¯eld in a slab doped with V-type atoms. The e®ect of relative phase between applied ¯elds on
linear and nonlinear dispersion and absorption is discussed. It is demonstrated that the system is
phase-sensitive when spontaneously generated coherence (SGC) exists. The e®ects of coupling
¯eld intensity, incoherent pump, and phase di®erence between probe and coupling ¯elds on Kerr
nonlinearity are also presented.