Effect of the incoherent population pumping on squeezing in a resonance fluorescence

The effect of the incoherent population pumping on the steady-state population inversion and the quadrature squeezing spectra produced in a resonance fluorescence of a two-level atom is investigated. In the presence of incoherent population pumping, the steady-state population inversion is increased for small frequency detuning but not changed for large frequency detuning. For the resonant excitation at low intensities, the weak incoherent pumping degrades the degree of the squeezing and shifts the position of the squeezing maximum. For the off-resonant excitation at strong intensities, the weak incoherent pumping hardly changes the squeezing spectra. But when the incoherent pumping is strong the squeezing may be completely destroyed for both cases.