Study On LD Pumped CW And Pulse Green Lasers

Laser diode-pumped solid-state green lasers have played an important role in basic research,industrial,medical and military fields,etc.,due to their advantages, such as the small size,high efficiency and stability.In this paper,LD-pumped continuous wave(CW)and pulse with high repetition green lasers are analyzed theoretically and studied experimentally.The mainly contents and research work can be summarized as follows.1.The developments of LD-pumped solid-state lasers are summarized.The present developments of LD-pumped solid-state green lasers are introduced briefly.2.The working characteristics of LD-pumped solid-state lasers in end-pumping and side-pumping ways are analyzed,such as the optical field distribution of pumping and oscillation beams,the thermal effect of gain medium.The physical,optical properties and level structures of Nd:YAG and Nd:YVO4 crystals are all presented.The general theory of second-harmonic generation is discussed.Phase matching of biaxial crystals and the influence of temperature are analyzed.The main properties of the nonlinear crystals KTP and LBO in frequency-doubled green lasers are described specially.The mechanism of "green problem" is analyzed,and methods for noise-suppressing are introduced.3.LD end-pumped electro-optic Q-switched pulse with high repetition green laser and LD side-pumped CW green laser are studied experimentally.a.In the experiment of LD end-pumped electro-optic Q-switched pulse with kHz repetition Nd:YVO₄ green laser,the maximum output power of 532nm green laser can be reached at 24A pumping current.When the modulated repetitions are 1kHz,2kHz and 3kHz,the maximum output powers are 218mW,226mW and 235mW respectively.The pulse width of green laser is 24ns at 18A pumping current,and the peak power is 7.42kW.b.LD side-pumped CW Nd:YAG green laser is also studied.Plane-plane linear resonator and KTP crystal for intracavity frequency doubling are adopted.The maximum power of 14.6W CW green laser is obtained when the pumping current is 24A.The conversion efficiency of 1064nm to 532nm is 40%.The power instability is less than 3%.At the same time,the output power of plane-concave-convex resonator is measured,and the maximum power of 12.8W green laser is obtained.4.The results in different conditions in the above experiments are analyzed contrastively and discussed respectively.The suggestions on optimization of the lasers are presented in the end.