Analysis and modeling of distributed feedback and distributed Bragg reflector lasers using regrowth-free index-coupled surface grating technology

The modeling of single-mode distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers based on an index-coupled surface grating on the InGaAs/InGaAsP multiple-quantum-well (MQW) structures is carried out. Such lasers require relatively simpler grating fabrication processes without multistep-epitaxial growth or regrowth, as required in conventional devices. A key concern for surface grating is designing structure that can provide sufficient feedback to achieve single-mode operation and high laser performance. Bragg wavelength operation of the surface grating (SG) DFB and SG DBR lasers can be satisfied by etching deep and fine gratings on the surface of both side portions and along the top of the ridge stripe, respectively. The numerical results obtained enable optimization of grating and laser geometries to provide the desired feedback effect. The simulated laser design shows that single-frequency operation at a wavelength of 1.55 mum with high a side-mode suppression ratio (SMSR) is attainable. (C) 2002 Society of Photo-Optical Instrumentation Engineers.