Focused ion beam implantation for gain coupled 1.55 μm DFB-laser diodes with improved device characteristics

Laterally gain coupled DFB lasers were fabricated by focused ion beam implantation with a new technological approach. On complete InGaAsP/InP laser structures ridge waveguides were defined and first order gratings were implanted laterally to the ridges. The subsequent rapid thermal annealing results in a periodic bandgap modulation by implantation induced intermixing and gives rise to a strong modulation of the absorption. An electromagnetic wave propagating along the ridge waveguide couples with the lateral grating which leads to single mode DFB emission. Simultaneously the increased bandgap reduces the overall absorption and improves the lateral carrier confinement which results in better laser performance compared to not implanted lasers.