Effect of carrier envelope phase on propagation of femtosecond chirped Gaussian laser pulse in a dense three-level Λ-type atomic medium

Abstract

By the numerical analyzing and simulation, we investigate effect of carrier envelope phase on propagation of femtosecond chirped Gaussian laser pulse in a dense three-level Λ-type atomic medium. It is shown that, when the small area 2π negative chirped pulses (or the 2π positive chirped pulses) with different value of initial carrier envelope phase φ0 propagate in the medium, splitting don’t occur and the chirped pulses evolve gradually to approximate normal Gaussian pulses with equal amplitude and group velocity, and the phase differences between them remain the same as the case of initial input pulses. When the 4π negative chirped pulses with different φ0 propagate in the medium, the pulses will split into at least two sub-pulses and the amplitude of the first sub-pulse is far more than the second sub-pulse; These first sub-pulses have equal amplitudes and propagating with equal group velocity in the medium, and the phase differences between these first sub-pulses remain the same as the case of initial input pulses; The amplitudes of these second sub-pulses are not equal and don’t change monotonously with linearly increasing of φ0 but take on a invert S-shaped pattern, and the phase differences between these second sub-pulses are different. The case of 4π positive chirped pulses is similar to the case of 4π negative chirped pulses, but the amplitudes of these second sub-pulses split off from the 4π positive chirped pulses have no obvious changes compared with the case of 4π negative chirped pulses.