  The entanglement of different classes of initially entangled qubit pair is
investigated in the presence of short laser pulses of rectangular and
exponential shapes with either one or both qubits are excited. For the
rectangular pulse, the detuning parameter protects the entanglement from
degradation and controls its upper and lower bounds. We show that the upper
bounds of entanglement decrease if both particles are excited, but the lower
bounds are much better if only one particle is excited. The phenomena of
entanglement degradation, sudden- death and -birth are shown for small initial
time. Long -lived entanglement behavior, but with a variable degree, appears in
the presence of rectangular pulse. However, in the case of the exponential
pulse one obtains an invariably long- lived entanglement. For the combined case
(rectangular $+$ exponential), we show that one can generate a long-lived
entanglement with small variable by increasing the strength of the rectangular
pulse area and decreasing the Rabi frequency of the exponential pulse.
