Zuo Junwei

33 W quasi-continuous-wave narrow-band sodium D-2a laser by sum-frequency generation in LBO

We demonstrate an all-solid quasi-continuous-wave (QCW) narrow-band source tunable to sodium D-2a line at 589.159 nm. The source is based on sum-frequency mixing between lasers at 1064 nm and 1319 nm in a LBO crystal. The 1064 nm and 1319 nm lasers are produced from two diode side-pumped Nd:YAG master oscillator power amplifier (MOPA) laser systems, respectively. A 33 W output of 589 nm laser is obtained with beam quality factor M-2 = 1.25, frequency stability better than +/- 0.2 GHz and linewidth less than 0.44 GHz. A prototype 589 nm laser system is assembled, and a sodium laser guided star has been successfully observed in the field test.

High Power Quasi-Continuous-Wave Diode-End-Pumped Nd:YAG Slab Amplifier at 1319 nm

We report a high power high beam quality quasi-continuous-wave (QCW) diode-end-pumped Nd:YAG slab amplifier at 1319 nm. The strongest 1064 nm parasitic oscillation has been successfully suppressed by reasonable coating design. In a five-pass configuration, the amplifier yields a 42.3 W linearly polarized 1319 nm output at repetition rate of 1 kHz with pulse duration of 75 μs and beam quality factors of Mx2 = 1.13 and My2 = 2.16 in the orthogonal directions. The fluctuation of the amplifier output power is measured to be ±0.6 %. Furthermore, a computational model of QCW pulse amplification is employed to examine the amplification process.

Progress on high power quasi-continuous-wave sodium beacon laser

A 33W 589 nm sodium beacon laser with the linewidth of 0.4 GHz and the beam quality of M2 = 1.2 is achieved by sum-frequency mixing 1064 nm and 1319 nm quasi-continuous-wave (QCW) diode-pumped Nd:YAG lasers with a LBO crystal. The repetition rate of the laser is 500 Hz with the pulse width of 120 μs. Compared with the continuous-wave (CW) sodium beacon laser, the QCW microsecond-pulse sodium beacon laser can provide a gatable pulse format to eliminate the interference of atmospheric Rayleigh scattering and reduce stretching phenomenon of the imaging spot for sodium guide star, so the better correction effect can be achieved by using the adaptive optics system with the microsecond-pulse laser. A microsecond-pulse sodium beacon laser prototype is developed to generate a sodium laser guide star which is observed by the 1.8m telescope in Yunnan province.