Uniform linear arrays of strained-layer InGaAs-AlGaAs quantum-well ridge-waveguide diode lasers fabricated by ECR-IBAE

Uniform linear arrays of strained-layer multiple-quantum-well InGaAs-AlGaAs ridge-waveguide diode lasers have been fabricated that operate near 980 nm and have low threshold currents I_th and high differential quantum efficiencies η_d. Uniformity was achieved by a combination of uniform ion-beam-assisted etching with an electron cyclotron resonance ion source and uniform organometallic vapor-phase epitaxial (OMVPE) growth. We investigated the effects of device geometry, namely, ridge width, cavity length, and remaining cladding thickness outside the ridge t, on I_th and η_d. For uncoated lasers with 500-μm-long cavities, 2- to 3-μm-wide ridges, and t=165±75 nm fabricated in double-quantum-well OMVPE material, I_th was typically in the range 6-7 mA and η_d was >40% per facet. A 24-element array of 2-μm-wide, 200-μm-long ridge-waveguide lasers with a high reflection coating on the back facet exhibited excellent uniformity, with threshold currents and single-ended differential quantum efficiencies that averaged 3.4 mA and 72%, respectively. Similar arrays with high-reflectivity coatings on both facets exhibited threshold currents as low as 2 mA