With the rapid development of laser technology, laser as the light source of night vision illuminating can realize long-distance and clear imaging, which has been widely used in laser active illuminating field. A high-power diode laser with a wavelength of 808 nm was designed as the laser active illuminating source, and the output power of no less than 100 W was obtained by spatial beam multiplexing, polarization multiplexing, and high efficiency fiber coupling techniques. In view of the beam homogenization of illuminating source, a novel beam homogenization system based on waveguide is proposed in this work. A square spot with a horizontal divergence angle of 40°, a vertical divergence angle of 10°, and an illuminating power ratio of 4:1 was obtained by a collimating lens. Comparing with the traditional circular illuminating beam, the square illuminating beam can match the illuminating angle of CCD camera better, and the energy utilization rate is higher. In addition, by optimizing the structure of waveguide and collimating lens, the illuminating angle can be changed to meet the illuminating requirements under different conditions theoretically.

In this research, the highly efficient external cavity feedback technology based on volume Bragg grating (VBG) is studied. By using the structure of a fast axis collimating lens, the beam transformation system, a slow axis collimating lens, and VBG, the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively, and the feedback efficiency of the external cavity is improved. Combined with beam combining technology, fiber coupling technology, and precision temperature control technology, a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping. The core diameter of the optical fiber is 1000 µm, the numerical aperture is 0.22, the output power from the fiber is 1013 W, the fiber coupling efficiency exceeds 89%, and the external cavity efficiency exceeds 91%. The central wavelength is 852.052 nm (in air), which is tunable from 851.956 nm to 852.152 nm, and the spectral linewidth is 0.167 nm. Research results can be used for cesium alkali metal vapor laser pumping.