Effects of pulse width on ultrahort laser pulse and spectrum and their carrier-envelope phase(CEP)dependence in a dense V-type three-level atomic medium are investigated with numerical solutions of a full Maxwell-Bloch equation without slowly varying envelope and rotating wave approximations.It is shown that:As pulse width is small,pulse splitting number is less,spectrum is wide,high-frequency part of the spectrum is significant,CEP has great effect on pulse and spectrum,particularly effect on time interval between sub-pulses and strength of high-frequency part is more obvious;As pulse width increasing,pulse splitting number increases,width of spectrum narrows and high-frequency part of the spectrum decreases gradually,effect of CEP on pulse and spectrum weakens gradually.

In one-photon resonance and detuning cases,effect of relative carrier-envelope phase(RCEP) on evolution of two-color sech-type femtosecond pulses and spectrum in a dense V-type three-level atomic medium is investigated with full Maxwell-Bloch equations.Modulation of RCEP on pulse shape and spectral property of two-color pulses in detuning case is more evident than that in single-photon resonance case.And in detuning case we get spectrum broadening much greater than that in resonance case.Supercontinuum with the highest frequency of 18 times of incident frequency appears.

With numerical solution of full Maxwell-Bloch equations obtained by finite-difference time-domain method and iterative predictor-corrector method,spatial distributions of pulse and populations of few-cycle laser pulse propagates in a ladder-type three-level atomic medium are investigated.It shows that,spatial distributions changes evidently with pulse area.As the pulse area is smallr,the pulse shape is irregular and oscillation time increases.As the pulse area is large,the pulse shape becomes relatively regular and oscillation times decreases evidently.With increasing of pulse area,amplitude and group velocity of pulse increase progressively,oscillation times of populations increase gradually and variation of spatial distributions of the pulse and populations at different moments decreases considerably.Moreover,spatial distribution of populations correlates closely to spatial distribution of the pulse.