Improvement of kink-free output power by using highly resistive regions in both sides of the ridge stripe for 980-nm laser diodes

Suppressing the lateral expansion of driving current by forming highly resistive regions at both sides of the ridge stripe in ridge-waveguide-type 980-nm laser diodes leads to an enhanced kink-free output power. The highly resistive regions are formed by hydrogen passivation of p-type carrier (Zn) on the plasma exposure in a mixture gas of methane and hydrogen. A simulation predicted a decrease in local gain in the lateral direction at both sides of the ridge stripe. Fabricated laser diodes with the highly resistive regions exhibit kink-free output power of over 500 mW, showing an increase in kink-free power of 85 mW on average with an increase of slope efficiency of about 10% compared to those without highly resistive regions.