Strained InGaAs/GaAs quantum well constricted-mesa lasers andapplication in a vertical-twin-guide tunable laser

Constricted-mesa semiconductor lasers containing a strained-layer InGaAs single-quantum-well-separate-confinement-heterostructure have been demonstrated. Very high etching selectivity between Al_xGa_1-xAs (x=0.9) and Al_xGa _1-xAs (x=<0.6) was achieved using diluted hydrofluoric acid to create a deeply undercut current confinement region, which enables a side contact for current injection. A process combining a self-aligned reactive ion etch and the undercut wet chemical etch has been developed for implementing a vertical twin-guide three-electrode tunable laser structure. Low-threshold currents for both single-guide devices with centered top contacts (5.2 mA) and twin-guide ones with side contacts (6.5 mA) were obtained