Semiconductor laser equipped with means for reinjecting the spontaneous emission into the active layer

Claim 1

A double heterostructure semiconductor laser with a reduced threshold current density, consecutively comprising: a substrate, a buffer layer, a first contact layer, part of the substrate and the buffer layer being etched down to the first contact layer, a first metal layer electrode located beneath the non-etched part of the substrate, on the etched part of said substrate and buffer layer and on said first contact layer, a confinement layer, an active layer emitting spontaneous and coherent radiations having a given wavelength, a second contact layer, a second metal layer electrode, said first and second contact layers being transparent to the wavelength of the spontaneous radiation emitted by the active layer, said spontaneous radiation being reflected by said first and second contact layers into said active layer where it is partly reabsorbed wherein the edges of said layers form a resonant cavity.