Low-threshold GaInAsSb/GaAlAsSb double-heterostructure lasers grown by LPE

Ga/sub 0.86/In/sub 0.14/As/sub 0.19/Sb/sub 0.87//Ga/sub 0.79/ Al/sub 0.27/As/sub 0.02/Sb/sub 0.98/ 2.2- mu m lasers grown by liquid-phase epitaxy (LPE) with the lowest threshold current density to date are reported. Using transverse far-field patterns and theoretical calculations for the fundamental mode, the value of the active layer refractive index is estimated as 3.78. It is shown that the development of low-threshold-current stripe lasers is limited by an excessive current spread in the low-resistivity p-type active layer. This is partly solved by making the active region n-type. The minimum I/sub th/ obtained for n-type active layers was 290 mA compared to 800 mA for p-type active layers, the broad-area threshold current being the same (3 kA/cm/sup 2/) in both cases.<
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