830-nm AlGaAs-InGaAs Graded Index Double Barrier Separate Confinement Heterostructures Laser Diodes With Improved Temperature and Divergence Characteristics

The 830-nm AlGaAs/InGaAs laser diodes (LDs) adopting multistep-graded index double-barrier separate confinement heterostructures (GRIN-DBSCHs) with small divergence beams and improved temperature characteristics under a high-output-power operation are reported. The double-barrier separate confinement heterostructure (DBSCH) design provides good carrier confinement and prevents current leakage by adding a multistep grading layer between cladding and waveguide layers. Simultaneously, the DBSCH design can facilitate reducing the divergence angle at high-power operation and widening the transverse mode distribution to decrease the power density around emission facets. In addition, the p-side doping depth is optimized to effectively raise the barrier height for reducing the electron overflow. Gaussian-like narrow far-field patterns are measured with the full-width at half-maximum vertical divergence angle to be between 11° and 13°. A threshold current of 16.5 mA and a slop efficiency of 0.98 W/A are obtained in the continuous-wave operation condition at room temperature. The maxima optical power densities of 21.5 MW/cm² per laser facet and good characteristic temperature values of threshold current (T₀) and slope efficiency (T₁) are achieved.