Continuous-wave oscillation of MQW DFB laser with air/semiconductor gratings embedded by mass-transport-assisted wafer fusion technique

Wafer fusion technique has been drawing much attention, since it can be applied to the integration of different materials and can offer new types of integrated devices. Recently, we have demonstrated a low threshold-current-density operation of MQW DFB laser with air/semiconductor gratings embedded by wafer fusion technique, where the additional phenomenon of mass-transport has been found to occur and improve the electrical characteristics at the fused interface. The fabrication of such air/semiconductor structures with submicron order inside the device without any crystal growth process is very useful to increase device designability. Moreover, the air/semiconductor gratings have potentially larger coupling coefficient, since the difference of refractive index between air and semiconductor is very large. In this work, we demonstrate for the first time the continuous-wave oscillation of the MQW DFB laser with the fused air/semiconductor gratings.