Angled cavity photonic crystal laser diodes with tilted sidewalls for improving far-field patterns

Angled laser diodes based on the longitudinal photonic band crystal (PBC) waveguide are first proposed and fabricated at a wavelength of 905 nm. Tilted sidewalls are utilized to reflect the light downward, thus enlarging the transverse mode size. In the experiment, continuous wave (CW) output power of 630  mW/facet is achieved, and stable and narrow divergence angles are obtained in the fast and slow axes, simultaneously. The transverse angle is reduced by 44% compared with that of the conventional broad area (BA) laser based on the same wafer, and the lateral angle is only 1.65° with on-axis main-lobe emission. This device shows a promising future for laser emission with ultra-narrow divergence and easy fabrication.