Nearly Diffraction-Limited and Low-Divergence Tapered Lasers With Photonic Crystal Structure

Tapered lasers emitting at 980 nm with photonic crystal structure are fabricated. A continuous wave power of 3 W is achieved with a peak power conversion efficiency of 35%. The beam divergences with full width at half maximum are below 16° in the vertical direction and 4° in the lateral direction at different currents. Nearly diffraction-limited beam qualities are obtained with a vertical M
²
value of 1.43 and a lateral M
²
value of 1.61. The vertical M
²
value is almost unchanged over the injecting current range of 2.5 A, indicating stable vertical mode operation of the device.