The output coupler, as a translucent dielectric mirror used in the laser resonator, can partially reflect the laser back to the resonator for gain amplification, and partly transmit the stable laser output. The constant reflectivity/transmittance ratio (R/T) of the output coupler is the main property of some mirrors in the resonator cavity. The pump power threshold, maximum output power and output efficiency of the laser are highly dependent on the R/T value of the output coupling mirror. Our output coupler, with a reflectivity of 70% to 99.5%, is made of sapphire/Nd-doped yttrium aluminum garnet (YAG), which delivers a high-power laser beam while avoiding absorbing light energy and thermal deformation. The reflectivity of the front surface is stable, and the laser coupling can be well modulated.