Waveguide Design for Long Wavelength InGaN Based Laser Diodes

One-dimensional optical waveguide calculations were performed to study the dependence of waveguide design on confinement factor (Γp) and optical losses ($\alpha_i$) of nitride laser diodes for emission wavelength ranging from 405 nm to 520 nm. We found that the conventional waveguide design containing GaN waveguide and AlGaN cladding layers known from violet laser diode does not support sufficient confinement of the optical mode for long wavelength devices (λ > 450 nm). We proposed a new design consisting of a thick InGaN waveguide which enhances the confinement. We compared the theoretical predictions with laser diodes grown by plasma assisted molecular beam epitaxy.