In-situ etching of patterned GaAs/InGaP surfaces for highly efficient 975 nm DFB-BA diode lasers

In-situ etching with CBr4 has been used to form buried Bragg gratings in AlGaAs-based broad area diode lasers with distributed feedback (DFB-BA) by pattern transfer into In0.49Ga0.51PIn0.49Ga0.51P within the MOVPE reactor. STEM/EDXS measurements show that the Bragg grating is finally formed by 10 nm thick In0.49Ga0.51PIn0.49Ga0.51P stripes that are fully embedded in AlxGa1−xAsAlxGa1−xAs. The oxygen sheet concentration at the regrowth interface is found by SIMS to be below 1×1016cm−2. DFB-BA lasers fabricated using in-situ etching of the grating reach optical output power >12W and peak wall-plug efficiencies >60%>60%.

► In-situ etching with CBr4 to do pattern transfer for Bragg grating formation.
► Direct regrowth on AlGaAs waveguide layers, subsequent to in-situ etching.
► Elimination of transport barriers and minimization of oxygen contamination.
► Record wall-plug efficiencies for DFB-BA diode lasers of 63%@7 W output power (15 °C heatsink temperature).