Xie Shiyong

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 Efficiency Multi-kW Diode-Side-Pumped Nd:YAG Laser with Reduced Thermal Effect

We demonstrate a high efficiency multi-kW diode-side-pumped Nd:YAG laser. High cooling efficiency of the diode-side-pumped module in the laser is achieved. The middle portion of the Nd:YAG rod in the module is cooled by a coolant jet with screwed side surface, and the end-caps of the rod without screwed side surface are cooled by Au coated on the surface. The thermal effect of the laser rod is reduced, which leads to high output power with high optical-optical conversion efficiency. By using three identical Nd:YAG laser modules, an output power of 4.2 kW and beam quality of 58 mm.mrad with an optical-optical efficiency of 35% at 1064 nm is obtained in a laser oscillator. By using four identical Nd:YAG laser modules, an output power of 3.1 kW and beam quality of 17 mm.mrad with an optical-optical efficiency of 25.8% is demonstrated in a master oscillator power-amplifier system.

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.

High power high beam quality diode-pumped 1319-nm Nd:YAG oscillator-amplifier laser system

This paper demonstrated a high power and high beam quality diode-pumped 1319-nm Nd:YAG master oscillator-power amplifier laser system. A thermally near-unstable resonator with four-rod birefringence compensation flat-flat cavity was adopted as the master oscillator. A solid etalon was inserted in the unidirectional ring resonator to compress the laser linewidth. Under a repetition rate of 500 Hz and pulse width of 160 μs, the master oscillator delivers an average output power of 16.8 W at 1319 nm with linear polarisation, beam quality factor M2 = 1.16 and linewidth of 3.2 GHz. A double-pass power amplifier with two amplifier stages was employed for higher power scaling and the output power was amplified to be 25.9 W with M2 = 1.43.

Q-Switched Tm:YAG Laser Intracavity-Pumped by a 1064 nm Laser

We report a Q-switched 2-μm Tm:YAG laser based on intracavity-pumped by a 1064-nm Nd:YAG laser operating at room temperature for the first time. An average output power of 5.1 W is obtained with the repetition rate of 30 kHz and a pulse width of 300 ns. In addition, we demonstrate a 12.5-W continuous-wave 2-μm Tm:YAG laser, which is, to our best knowledge, the highest power for intracavity-pumping configuration.

Tunable and narrow linewidth yellow beam generation by sum-frequency mixing of diode-pumped Nd:YAG ring lasers

Output power of 1.1 W and linewidth of 0.7 GHz and beam quality of M2 = 1.2 yellow beam was generated by sum-frequency mixing 1064 nm and 1319 nm radiations of quasi-continuous-wave diode-pumped Nd:YAG lasers inside a pair of KTP crystals. The narrow linewidth 1064 nm and 1319 nm beams were realized by inserting solid etalons in the three-mirrors ring resonators. The wavelength of yellow laser was adjusted and controlled by the control of etalon angle and temperature. To achieve the high beam quality at the average power, thermally near-unstable resonators with two-rod birefringence compensation were designed and employed in the 1064 nm and 1319 nm ring lasers. The high sum-frequency efficiency was obtained by using a pair of KTP crystals with a walk-off-compensated configuration. The power of the diffraction-limited, narrow linewidth and precise-tunability yellow laser was reached to 1.1 W by mixing the 1064 nm beam of 7.5 W and the 1319 nm beam of 3.2 W.

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.

589nm high power sum-frequency generation with quasi-continuous-wave diode-pumped Nd:YAG lasers

A 12.7 W 589 nm coherent light source with the linewidth of less than 1 GHz and the beam quality of M2 = 1.2 is achieved by extra-cavity sum-frequency mixing 1064 nm and 1319 nm quasi-continuous-wave diode-pumped Nd:YAG lasers with a LBO crystal.