Blue laser is widely used in laser medicine,optical high density storage,laser color display etc.Due to the limitation of laser crystal by the frequency doubling it is difficult to direct obtain blue laser band of 480nm-500 nm.So in recent years,sum frequency for obtaining blue laser has became an important research direction.But at this stage,the problems of gain competition and the ratio of photon-number influence the method of sum frequency for obtain blue laser,and the problems lead to can't obtain the blue laser of ideal power and beam quality.To solve above problems and obtain high power and better beam quality blue laser,a new method based on intracavity-pumped for 491 nm blue laser is put forward in this paper.We conduct the research from the following aspects in this paper.The intra-cavity pumping dual-wavelength model based on quasi-three-level and four-level rate equation is built.Based on this intra-cavity laser model,the changes of photon-number in different condition is simulated.Comparative analysis of the influence of sum frequency efficiency combined with laser wavelength is carried out.The optimum conditions for achieving the photo number ratio of 1:1 is obtained by comparing and analyzing the efficiency of the combination of quasi-three-level and four-level laser with different wavelengths.Finally,the 912 nm and 1064 nm fundamental frequency laser are used for intracavity pump dual-wavelangth lasers sum frequency.The resonant made of intracavity pump model is designed,and the laser cavity length of quasi-three-level and four-level is determined to be 70 mm and 45 mm through optimization and comparison.From the sum frequency three-wave coupling equation and its phase matching condition,the LBO nolinear sum frequency crystal is determined to 10 mm in length and the best matching angle is ?°= 90,?°= 6.16 based on the frequency conversion efficiency.The experimental study is carried out on the basis of the theoretical model of intracavity pumping,using a compact straight cavity structure by taking the advantage of all-solid-state laser miniaturization to obtain the 912 nm,1064nm dual-wavelength output,on this basis,the photon number ratio in the cavity is optimized by using the longer 10 mm four-level crystal according to the theoretical simulation,when the quasi-three-level crystal absorption of 808 nm pump power is 14.45 W and the output mirror with 1064 nm transmittance is 5%,912 nm transmittance is 2%,the dual-wavelength total output power is 2.4W and the intracavity power can be calculated up to 50 W or more accordingly.A stable 491 nm blue laser output of 142 mW was obtained after inserting the LBO nolinear sum frequency crystal as well as change the output mirror to blue laser high transmittance fundamental frequency laser total reflection output mirror,the light-light conversion efficiency reache 0.98%. |