Quantum-Dot Surface Emitting Distributed Feedback Lasers Using Indium–Tin–Oxide as Top Claddings

We demonstrate InAs/InGaAs quantum-dot surface emitting distributed feedback (SE-DFB) lasers, using an indium-tin-oxide layer as top cladding, which eliminates the regrowth process used in conventional DFB lasers to greatly simplify laser process. The lasing peak near 1.30 μm realized using the grating period of 375 nm exhibited a 0.13-nm linewidth and a low-temperature red-shift rate of 0.1 nm/K. The laser had a threshold current density of 210 A/cm² and a characteristic temperature of 94.6 K. The surface emitting laser light had the divergence angles of less than 1° and 8°~9° along and perpendicular to the grating direction, respectively.