High-Brightness Low-Divergence Tapered Lasers with a Narrow Taper Angle

High-brightness tapered lasers with photonic crystal structures are designed and fabricated. A narrow taper angle is designed for the tapered section. The device delivers an output power of 3.3 W and a maximum wall-plug efficiency of 43%. The vertical beam divergence is around 11^\circ at different currents. Nearly diffraction-limited beam qualities for the vertical and lateral directions are obtained. The lateral beam quality factor M^2 is below 2.5 and the vertical M^2 value is around 1.5 across the whole operating current range. The maximum brightness is 85 MW\cdotcm^-2sr^-1. When the current is above 3.3 A, the brightness is still above 80 MW\cdotcm^-2sr^-1.