An indium gallium arsenide-gallium arsenide-aluminum gallium arsenide laterally-coupled distributed feedback ridge laser diode

Single-mode distributed feedback (DFB) laser diodes typically require a two-step epitaxial growth or use of a corrugated substrate. A novel technique to achieve stable single-mode oscillation laser diodes that eliminates the need for epitaxial regrowth has been developed. We demonstrate InGaAs-GaAs-AlGaAs DFB lasers fabricated from a single epitaxial growth using lateral evanescent coupling of the optical field to a surface grating etched along the sides of the ridge. A CW threshold current of 25 mA and external quantum efficiency of 0.48 mW/mA per facet were measured for a 1 mm cavity length device with antireflection coated facets. Single-mode CW output powers as high as 11 mW per facet at 335 nm wavelength were attained. A coupling coefficient of at least 5.8 cm...