Low Threshold PbSnSeTe-PbSeTe Lattice-Matched Double-Heterostructure Lasers

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Abstract
Very low threshold current density lasers with an 11 µm emission wavelength at 4.2 K have been fabricated from the lattice-matched Pb0.85Sn0.15Se0.02Te0.98-PbSe0.08Te0.92 DH wafers grown by liquid phase epitaxy on a Pb0.8Sn0.2Te substrate. The active layer thickness, which minimizes the threshold current density, has been determined to be about 1 µm from the calculated optical confinement factors assuming a linear gain-current relationship. Lasers with a 1 µm active layer thickness and a 500 µm cavity length exhibited threshold current densities as low as 65 A/cm2 at 4.2 K and 350 A/cm2 at 77 K. The measured internal optical loss was as low as 2.8 cm-1 at 4.2 K.