Fabrication of a high-performance InGaAsP/InP integrated laser with butt-coupled passive waveguides utilizing CH4/H2 reactive ion etching

We obtained high-performance 1.3 mu m InGaAsP/InP buried heterostructure lasers integrated with butt-coupled waveguides using reactive ion etching (RIE) for mesa definition, brief chemical cleaning for damage relief and low-pressure metalorganic vapour phase epitaxy for the epitaxial layer growth. We measured a coupling efficiency between the active layer and the passive waveguide layer of over 91 +/- 1.6% per facet across a quarter of a 2 inch InP wafer. The threshold current and the slope efficiency were 13 mA and 0.26 mW mA(-1), respectively, of the 700 mu m long integrated laser. This excellent uniformity and high performance demonstrate that RIE coupled with slight chemical treatments can be successfully used to fabricate high-quality integrated photonic devices. Transmission electron microscopy observation revealed RIE-induced strains and dislocation loops around the etched mesa after the regrowth, which were proposed to be responsible for the inferior characteristics of the lasers with mesas that were reactive ion etched but had not been cleaned in HBr-based solution.