Abstract
We investigate the absorption-dispersion spectra of a weak signal field probing a system of 2-level atom coherently driven by a non-resonant mono-or bi-chromatic laser field of arbitrary strength and damped by a non-resonant squeezed vacuum radiation reservoir. In particular, we utilize our iterative analytic solutions of the non-autonomous model Bloch equations to obtain computationally the zero-absorption isolines in the (Delta, Omega)-plane at resonant or Rabi-side probe field frequency (Delta=atomic frequency detuning, Omega=Rabi frequency of the driving field). By product, the accompanied regions of finite or steep variation dispersion are identified.