UNIFORM LINEAR ARRAYS OF STRAINED-LAYER INGAAS-ALGAAS QUANTUM-WELL RIDGE-WAVE-GUIDE DIODE-LASERS FABRICATED BY ECR-IBAE

Uniform linear arrays of strained-layer multiple-equantum-well InGaAs-AlGaAs ridge-waveguide diode lasers have been fabricated that operate near 980 mn and have low threshold currents I-th and high differential quantum efficiencies eta(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 eta(d). For uncoated lasers with 500-mu m-long cavities; 2- to 3-mu m-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 eta(d) was >40% per facet, A 24-element array of 2-mu m-wide, 200-mu m-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.