Comparison of output power of InGaN laser diodes for different Al compositions in the AlGaN n-cladding layer

The output power of InGaN multiple-quantum-well laser diodes (LDs) emitting at 405 nm wavelength is compared for several Al composition in the AlGaN n-cladding layer. The Al composition has been varied from 2% to 6% to study the effect of n-cladding refractive index on threshold current and slope efficiency of the LDs. As the Al composition in the AlGaN n-cladding layer increases, both threshold current and slope efficiency decrease. This behavior can be explained by the change in optical field distribution with refractive index of the AlGaN n-cladding layer. It is found that the Al composition of ≤4% would be advantageous for achieving more than 100 mW output power and high level of catastrophic optical damage.