GaAs–AlxGa1−xAs Double Heterostructure Injection Lasers

Double heterostructure GaAs–AlxGa1−xAs junction lasers which have very low thresholds and which have been operated continuously at and above room temperature have been fabricated by liquid phase epitaxial growth. The threshold current density of these lasers decreases approximately linearly with the thickness of the active region from 3 to at least 0.5 μm. This is interpreted as the result of near perfect carrier and optical confinement as the result of large steps in the energy gap and index of refraction at the heterojunctions in these diodes. The gain in these lasers is very high and its dependence upon current density is superlinear. Loss is very low and almost that expected from free carriers. Complete polarization of the lasing mode was observed. This latter is interpreted to be the result of an increased reflection coefficient for the T E mode.