Research On High Power Diode Laser External Cavity Beam Combination And White Laser

Diode lasers have many advantages,such as long life,high electro-optic conversion efficiency,large power-volume ratio,excellent modulation performance,wide optional wavelength and easy integration.With the continuous improvement of power,brightness,beam quality and spectral stability,diode lasers have been directly or indirectly used in space communication,laser processing,laser illumination and display,laser measurement and monitoring,national defense and security et al.The market of diode lasers is expanding all over the world.As an indirect light source,diode lasers pumping solid,optical fibers and alkali metals and other types of lasers require strict matching between the pumping spectrum and the absorption spectrum,while diode lasers have the problems of wider spectrum and poor spectral stability,resulting in lower pumping efficiency.As a direct energy source,the problems of low power and poor beam quality need to be solved urgently.In addition,the synthetic light source based on red,green and blue(RGB)three-color diode lasers is applied in the field of laser display and lighting.It has the advantages of good color rendering and high brightness.However,due to the problem of low laser power in the initial stage,it can not meet the requirements of high power and high brightness laser display.In this paper,based on the feedback wavelength locking and beam combination technology of diode lasers,a direct light source with high power and beam quality as well as a high power and narrow linewidth pump light source suitable for alkali metal vapor laser pumping are developed.A high power white laser display light source based on RGB trichrome diode lasers is developed.Specific research contents and results are as follows:(1)Based on RGB trichrome diode lasers,the trichrome light is coupled into a single fiber through spatial beam combining and wavelength beam combining,and the output power of the optical fiber is more than 100W.According to the principle of chromaticity,the white light output with 63W power and 5710K color temperature is obtained.Compared with the standard white light D65,the color temperature deviation is less than 12.2%.On this basis,the white light output with a power of 58.4W and a color temperature of 6480K was obtained by temperature and color adjustment experiments.Compared with the standard white light D65,the color temperature deviation is less than 3.08%.Based on this light source,combined laser output with different color temperatures can be realized by adjusting the laser power ratio.(2)To meet the pumping requirements of Rb alkali metal vapor laser,a“FAC+BTS+SAC+RVBG”structure is proposed.By compressing the divergence angle of laser incident to RVBG and improving the effective feedback rate of RVBG,a 780-nm narrow-line-width diode laser with a spectral width of 0.064nm(FWHM)is developed to further refine the structure.The temperature controlled RVBG can stabilize the central wavelength at 780.00 nm,the temperature drift coefficient is 0.0012nm/?,the current drift coefficient is 0.0013nm/A,and the continuous power reaches47.2W.Based on this structure,the output power of the four wavelength controllable laser linear array is 173.8W,and the electro-optic conversion efficiency is 46.6%.(3)Based on single-line 800-nm diode lasers,19 laser units have been synthesized and their spectral widths are 3.94 nm,the spacing between adjacent peaks is about 0.22nm,the output power is 31 W,the electro-optic conversion efficiency is 51.5%.On this basis,a spectral beam combination of four 800 nm diode laser linear arrays are realized.(4)A novel laser-coupling structure is proposed,in which the same transmission grating is simultaneously employed by two spectral beams generated in identical resonant cavities.The novel structure doubles the number of coupled laser emitters and the output power.Eight 800-nm diode laser bars were coupled and combined with polarization multiplexing,achieving a continuous wavelength power of 212 W,an M~2beam quality of 2.2×16.7 and a brightness tens of times higher than that of commercial fibers(100?m/0.22NA,800 nm,100W).