Waveguide structural effect on ripples of far-field pattern in 405nm GaN-based laser diodes

We investigated the dependency of waveguide structures on ripples of far-field patterns in 405nm GaN-based laser diodes theoretically and experimentally. As the n-type cladding layer thickness decreases, the passive waveguide modes strongly interact with an active layer mode. This suggests that the thicknesses of n-AlGaN/GaN superlattice clad and n-GaN waveguide layers have significant influences on FFP ripples. We successfully obtained very smooth far-field patterns perpendicular to the junction plane by optimizing both n-AlGaN/GaN clad layer thickness and n-GaN waveguide layer thickness.