Elimination of leakage of optical modes to GaN substrate in nitride laser diodes using a thick InGaN waveguide

A novel design consisting of a thick InGaN waveguide is proposed to fully eliminate leakage to the GaN substrate in nitride laser diodes. The design is based on the effective refractive index engineering and does not require the commonly used thick AlGaN claddings. The conditions required to fully eliminate the optical leakage are discussed. Experimental results from eight blue laser diodes with different indium contents and thicknesses of the InGaN waveguide grown by plasma-assisted molecular beam epitaxy are presented to validate the theoretical results.