  We report on the generation of nanosecond mid-infrared pulses having
frequency tunability, a narrow linewidth, and a high pulse energy. These pulses
are obtained by frequency mixing between injection-seeded near-infrared pulses
in potassium titanyl arsenate crystals. A continuous-wave external cavity laser
diode or a Ti:sapphire ring laser is used as a tunable seeding source for the
near-infrared pulses. The typical energy of the generated mid-infrared pulses
is in the range of 0.4-1 mJ/pulse. The tuning wavelength ranges from 3142 to
4806 nm. A narrow linewidth of 1.4 GHz and good frequency reproducibility of
the mid-infrared pulses are confirmed by observing a rovibrational absorption
line of gaseous carbon monoxide at 4587 nm.
