High-power QCW microsecond-pulse solid-state sodium beacon laser with spiking suppression and D-2b re-pumping

摘要

A 65 W quasi-continuous-wave microsecond-pulse solid-state sodium beacon laser tuned to the sodium D-2a line has been developed with a linewidth of 0.3 GHz, beam quality of M-2 = 1.38, and pulse width of 120 mu s at a repetition rate of 500 Hz by sum-frequency mixing 1319 and 1064 nm diode-pumped Nd:YAG master-oscillator power-amplifier systems. The laser wavelength stability is less than +/- 0.15 GHz through feedback controlling. The laser spiking due to relaxation oscillations is suppressed by inserting frequency doublers in both 1319 and 1064 nm oscillators. Sodium D-2b re-pumping is accomplished by tuning the frequency of the electro-optic modulator with the right D-2a -D-2b offset. A bright sodium laser guide star with a photon return of 1820 photons/cm(2)/s was achieved with the laser system when a 32 W circular polarized beam was projected to the sky during our field test at the Xinglong Observatory. (C) 2016 Optical Society of America