A simplified multiwavelength prototype of an axially symmetric diode laser device based on stacks made of single emitters has been made, and the performance of the device has been demonstrated experimentally. The results verify that kilowatt-level light power can be focused into a circular spot with a 1/e^2 diameter of 360\text{\hspace{0.17em} μm} , a focal length of 100\text{\hspace{0.17em} mm} , and a numerical aperture of 0.24, thus producing an average power density in excess of 10\text{kW}/{\text{mm}}^{\text{2}} and a brightness of 6\times {10}^{10}{\text{W \hspace{0.17em}m}}^{-2}{\text{sr}}^{-1} . The experiments also predict that it will be possible to increase these values to more than 60\text{kW}/{\text{mm}}^{\text{2}} and 3\times {10}^{11}{\text{W \hspace{0.17em}m}}^{-2}{\text{sr}}^{-1} .