Development of high-pulse energy Ho:Tm:YLF coherent transmitters

NASA Langley has developed a diode-pumped, room temperature Ho:Tm:YLF coherent pulsed transmitter for SPARCLE, a NASA approved space shuttle mission. The acronym stands for SPAce Readiness Coherent Lidar Experiment and is expected to fly in 2001. SPARCLE mission objective is to carry out first ever global wind measurement from space. The laser transmitter for SPARCLE is a Ho:Tm:YLF power oscillator operating at eye-safe wavelength of 2.05 mu m. The Q-switched output energy is 125 mi at six Hz, and it has a near-transform limited beam with a pulse width of 170 ns. The high power and high beam quality of this laser makes it well suited as a coherent wind lidar transmitter on a space platform. When the output of this power oscillator is amplified by using four diode-pumped Ho:Tm:YLF amplifiers, an output energy of 600 mi at 10 Hz has been achieved. This is the highest energy ever produced at 10 Hz, and is at least an order of magnitude greater than previously achieved for 2- mu m diode-pumped laser at room temperature.