Study On Efficient And Stable GTR-KTP Intracavity Frequency Doubled Cr,Nd:YAG Self-Q-switched Green Laser

Laser diode(LD)directly pumped solid-state green laser combined with Q-switched technology and direct pumping technology not only alleviate the thermal effect of the solid-state laser,but also can effectively shorten the cavity length of the laser to produce high peak power,repetition rate and narrow pulse width of the green pulse,and the structure is relatively simple and easy to implement the laser of the miniaturization.In order to obtain highly efficient and stable green laser pulses in a Cr,Nd:YAG/GTR-KTP intracavity frequency doubled self-Q-switched green laser under direct pumping,experimental and theoretical researches on the length of frequency doubling crystal,cavity length,NdVU doping concentration of gain crystal are studied in this thesis.First of all,the progress of the LD pumped all-solid-state green laser has been introduced.Shortcomings and problems of generating green laser pulses by the traditional methods are also pointed out.Then,the theory of nonlinear frequency conversion is discussed and the impact of the nonlinear conversion efficiency factors is analyzed.The influence of Nd3U doping concentration on the fluorescence lifetime,absorption coefficient and fluorescence quantum efficiency is investigated.Secondly,when the cavity length is set to 13 mm,7-mm-long GTR-KTP crystal and 5-mm-thick Cr,Nd:YAG crystal are used in the laser frequency doubling experiment,high efficiency and stable pulse green laser pulses at room temperature are achieved.The average output power of 200 mW is obtained at the absorbed pump power of 1.65 W,and the corresponding optical-to-optical conversion efficiency is 12.1%.The highest optical-to-optical conversion efficiency has been achieved in the same condition.At the same time,output green laser with pulse energy greater than 8?J,pulse width of 8.8 ns and peak power exceeding 1 kW is obtained.When the average output power of Cr,Nd:YAG/GTR-KTP intracavity frequency-doubled self-Q-switched green laser is 131 mW,the green laser is operated at room temperature for 2 hours,and its average output green power jitter is less than 2.1%.Finally,the rate equations of intracavity frequency doubling self-Q-switched lasers are used to simulate the laser performance and simulated results are in good agreement with the experimental results.Based on the simulated results and experimental results,the effects of the gain medium with different Nd3+ doping concentration and thickness on the pump power threshold and the green laser output power are further investigated with the help of the rate equations.When the pump power is set to 2 W,the maximum average output power is obtained with the gain medium doped with 3 at.%Nd3+ ions and 6 mm of the thickness.At this time,average output power of 380 mW is achieved,and the corresponding optical to optical conversion efficiency is 19%.The green laser performance has been effectively improved.This provides a theoretical basis for the design and optimization of efficient and stable GTR-KTP intracavity frequency doubled Cr,Nd:YAG self-Q-switched green laser.It also provides to a new method for developing highly efficient,short pulse miniature green laser.