VBG can be divided into transmission type and reflection type. It can combine lasers of various wavelengths, and the beam quality of the laser will be greatly improved when combining the laser beam. Besides, VBG is not affected by temperature, and can withstand high power laser irradiation, so it is an ideal component for laser beam combining. VBG can combine multiple laser beams with similar wavelength, thus several doubling the output power of the laser.