  We have developed experimental methods for the generation of chirped laser
pulses of controlled frequency evolution in the nanosecond pulse length range
for coherent atomic interaction studies. The pulses are sliced from the
radiation of a cw external cavity diode laser while its drive current, and
consequently its frequency, are sinusoidally modulated. By the proper choice of
the modulation parameters, as well as of the timing of pulse slicing, we can
produce a wide variety of frequency sweep ranges during the pulse. In order to
obtain the required frequency chirp, we need to stabilize the center frequency
of the modulated laser and to measure the resulting frequency evolution with
appropriate temporal resolution. These tasks have been solved by creating a
beat signal with a reference laser locked to an atomic transition frequency.
The beat signal is then analyzed, as well as its spectral sideband peaks are
fed back to the electronics of the frequency stabilization of the modulated
laser. This method is simple and it has the possibility for high speed
frequency sweep with narrow bandwidth that is appropriate, for example, for
selective manipulation of atomic states in a magneto-optical trap.
