INJECTION-SEEDED PULSED ALEXANDRITE LASER FOR DIFFERENTIAL ABSORPTIONLIDAR APPLICATION

We describe a Q-switched alexandrite laser injection seeded with a cw single-mode titanium-sapphire laser. The reported experimental results show that this system meets the frequency stabilization required for differential absorption lidar measurement of humidity, pressure, and t emperature. The emission of the cw titanium-sapphire master oscillator is locked to an atmospheric absorption line by means of a servoloop w ith derivative spectroscopy. The spectral position is stabilized withi n 3.5 x 10(-4) cm-1 (10 MHz) of the peak of the line over 1 hr. The al exandrite laser emits pulses of 30 mJ in 500 ns, with a spectral linew idth of almost-equal-to 3.3 x 10(-3) cm-1 (100 MHz). The position of t he centroid of the emitted spectrum has a standard deviation of 6 x 10 (-4) cm-1 (18 MHz) and is held within +/- 1.3 x 10(-3) cm-1 (40 MHz) o f the peak of the absorption line over 1 h.