Hydrostatic pressure measurements ( 12 kbar) on single- and multiple-stripe quantum-well heterostructure laser diodes

Short wavelength Alx′Ga1−x′As-AlxGa1−xAs (x′∼0.85, x∼0.22) quantum-well heterostructure (QWH) laser diodes (well size Lz ≊400 Å) that operate continuously (cw) at 300 K are subjected to hydrostatic pressure (≲12 kbar). The emission spectrum and the light intensity versus current (L-I) curves are monitored to determine the pressure dependence of the direct (Γ) band gap and the threshold current. The band gap exhibits a linear pressure dependence with a noticeable change in slope at ∼4.5 kbar, similar to previously reported results for AlxGa1−xAs-GaAs QWH diodes. The threshold current increases monotonically with pressure, reflecting the increasing loss of carriers to the X and L bands. The short-wavelength cw limit of the system, i.e., a gain-guided laser with a 400-Å AlxGa1−xAs (x∼0.22) quantum well and no separate waveguide region, is determined to be ∼6980 Å.