The transient fluorescent spectrum of a non-dissipative single 2-level atom
driven by a resonant rectangular pulse is investigated analytically and
computationally with the Haar wavelet window function. The shift parameter
(k) of the mother wavelet function induces periodic effect. For weak
pulse, a central dip structure -characteristic of the window transmission
lines- occurs in the spectrum. With initial atomic coherent state and for
strong pulse and large (k), interference of the strong Rabi oscillations
induces asymmetrical dense ’ringing’ around the two Rabi side bands of
the spectrum.