Low-loss III-IV photonics and high efficiency grating couplers incorporating low-index AlOx layers

We demonstrate a GaAs based Quantum Dot (QD) optoelectronic integration platform with results for surface grating couplers (SGC) and edge emitting lasers. SGCs usually perform poorly in systems without a large refractive index contrast and here we utilize thin oxidized Al0.98Ga0.02As layers to overcome this issue. The results show an increase from 10% to 30% in surface grating coupling efficiency, for the unoxidized compared to oxidized, and substrate-loss decrease from 70% to 20%. Electrically pumped edge-emitting lasers on the same platform exhibit comparable performance to more standard 1300nm QD designs. We describe the design, fabrication and characterization of these devices.