High power vertical-cavity surface-emitting laser array with small divergence

High power vertical cavity surface emitting laser (VCSEL) array with small divergence angle is reported. By choosing the large aperture size and enlarging the centre spacing of the elements, the resistance and thermal resistance of the array are reduced. The two-dimensional 4×4 array with element mesa diameter of 250 μm, oxide aperture of 200 μm and center to center spacing of 280 μm has a higher output power than that of the single device which has the same active area. The maximum output power is 1.81 W at a current of 6 A at room temperature. The threshold current is 1.2 A with a slop efficiency of 0.37 W/A, and the differential resistance is 0.01 Ω. The causes of the higher order transverse mode in the array element are analyzed by simulating the current density profiles in the active region. The far-field divergence angle is suppressed from 30° to less than 15° by using an extra Au layer. There is a slight drop in output power due to the introduction of the extra Au layer. The aging test is carried out under constant current mode at 60°C and the result shows that the total degradation of output power is less than 10% after 800 h.