Research On High-Power Quasi-CW440nm Blue Laser

440nm laser has a wide applications in laser display, biological, medical and marine exploration. In this thesis we use LD side-pumped Nd:YAG and acoustic-optical Q-switch to produce1319nm pulse laser. Frequency doubling of1319nm with I phase matching LBO to obtain660nm.440nm laser is achieved by1319nm and660nm sum-frequency with I phase matching LBO.The application and current situation of blue laser are introduced. To analyze the laser crystal threshold, thermal distribution, thermal stress and thermal lens effect. Discuss the analytical solution of the acoustic-optical Q-switch rate equation. Combine with the three-wave coupled equations to discuss the impact of frequency conversion efficiency. Design cavity length by the transfer matrix of the Gaussian beam in the resonant cavity. Simulate the best match angle by the dispersion equation and phase matching type of LBO crystal.Set up experimental of1319nm fundamental frequency to study the power and wavelength, When the1319nm power is123W to obtain the440nm average power of6.8W, the conversion efficiency is5.5%.