Jianguo Wen

Recirculating gas flow, coaxial geometry CO2 laser

A sealed‐off transversely excited atmosphere CO2 laser with a gas internal coaxial circulation scheme is presented. Long‐lived (106 shots) stable glow discharges at a pulse repetition frequency up to 33 Hz are demonstrated. The minimum clear ratio is found to be smaller than Dzakowic’s theoretical limit [G. S. Dzakowic and S. A. Wutzke, J. Appl. Phys. 44, 5061 (1973)].

Optimization of the peak power of Q-switched diode-pumped lasers

The Q-switching technique of LD pumped Nd:YAG laser with high repetition and short pulse-width was studied. According to the theoretical and experimental research, the way to obtain the optimal pulse parameters was presented, which is the theoretical and experimental base for increasing peak power and decreasing pulse width of a Q-Switched laser output pulse. It is of great value for the research of light source of the laser space communication and laser imaging. Q-switching technique is the key technique of the output pulse of DPL. By using the rate equations, the numerical solution for the trace of a giant pulse and simple expression for the peak power are derived. Therefore the crucial factors of the peak power and the pulse width are the ratio of the initial to the final population inversion ni/nt and the photon decay time tc. As ni/nt increases and the tc decreases, the peak power goes up and the pulse width goes down. From which the optimal parameters of an output pulse can be obtained. According to the analysis above, the way to obtain the optimal pulse parameters was put forward as follows. The power of pumping LD should be as high as possible, while the resonator length as small as possible, and the corresponding optimum reflector should also be selected.

Channel selection technology in acousto-optic Q-switch

The performance of Q-switch DPL output giant pulse can be optimized by utilized the site of maximum diffraction efficiency of acousto-optic Q-switch. Based on the model of spot acoustic source, spatial distribution of ultrasound field in acousto-optic crystal is studied by numerical calculation with considering the factor of acoustic attenuation. Distribution of diffraction efficiency in acousto-optic crystal is obtained by analysis it. So the site of maximum diffraction efficiency is found, and the same outcome is obtained in experiment. The channel selection technology is put forward based on the study on spatial distribution of diffraction efficiency in acousto-optic crystal that is benefit to obtain optimal parameters (which include the peak power, pulse width, etc) in DPL.

Compact sealed-off TEA CO2 laser

A transversely excited atmospheric (TEA) CO2 laser with gas internal coaxial circulation scheme is presented. To ensure stable discharge the free potential plate UV corona preionization technique is employed. The gas flow velocity reaches 15 meters per second, when the motor rotates at 8000 turns per minute. The TEA CO2 laser is able to operate at 33Hz with more than 106 arcing-free discharge. The minimum clear ratio is found smaller than theoretical limit (root)3.