Abstract
Continuously graded‐index separate confinement heterostructure multiple quantum well (four wells, Lz ∼50 Å) lasers fabricated in the Ga1−xInxAs1−yPy/InP system with lattice‐matched quaternary wells (bulk emission wavelength λg=1.39 μm) and barriers (λg=1.2 μm) are reported. A 5‐μm‐wide ridge waveguide laser operates with laser threshold current Ith=34 mA at room temperature (λ∼1286 nm) with an external differential quantum efficiency of ∼19% per facet and a temperature coefficient T0 ∼40 K. Large‐area threshold current density is measured at 1.1 kA/cm2 on a 40×300 μm2 device.