Vertical cavity surface emitting laser with a submonolayer thick InAs active layer

We report photopumped operation of a vertical cavity surface emitting laser where the active region consists of a single pseudomorphic InAs-GaAs quantum well that is less than one monolayer thick. This represents the thinnest active layer to support stimulated emission when the optical feedback is perpendicular to the layer. Lasing action supported across a submonolayer thick quantum well can be understood by considering the effects on the carrier collection process and the gain across an ultrathin quantum well due to the spreading out of the electron and hole wavefunctions. Pulsed lasing due to gain across the InAs quantum well is confirmed for photoexcitation energies above and below the band edge of the GaAs confining layers at 17 and 77 K.