Gallium arsenide (GaAs) lasers at 1.3 and 1.55 µm have received a lot of attention in the past several years for their potential as inexpensive, high-speed, uncooled sources for telecommunications. With careful optimization of metamorphic crystal growth, structure, and optical properties, researchers at Chalmers University of Technology (Gothenburg, Sweden) and the Chinese Academy of Sciences (Beijing, China) have demonstrated metamorphic 1.58 µm indium gallium arsenide (InGaAs) quantum-well lasers that may be a promising alternative to 1.55 µm GaAs-based lasers.
The metamorphic InGaAs quantum-well laser was grown by molecular beam epitaxy on an n-type GaAs substrate using a low growth temperature of 440ºC and post growth rapid thermal annealing, using antimony as a surfactant and inserting thin GaAs smoothing layers. The resulting broad-area laser measured 50 × 1250 µm with a threshold current density of 490 A/cm2 at room temperature under pulsed operation. The root-mean-square surface roughness of the 6-µm-thick laser structure, as measured by atomic-force microscope over 1 and 10 µm2 areas, are 0.5 and 5.6 nm, respectively. Contact Ivar Tångring at [email protected].