1.55 /spl mu/m complex-coupled DFB lasers with quaternary overgrown gratings

We have demonstrated 1.55 /spl mu/m complex-coupled BH-DFB lasers by employing for the first time GaInAsP overgrowth of the chemically assisted ion beam etched (CAIBE) gratings. The gratings were formed by etching partly the MQW's to increase the gain-coupling. Although CAIBE was used for etching the gratings, the threshold current was less than 20 mA and the lasers exhibit stable single mode operation with a very large side-mode suppression ratio (SMSR) up to 55 dB.