An optical device comprising: a first active stack of layers comprising an optical cavity, at least one quantum dot located in said cavity; an upper contact provided above said optical cavity; a lower contact provided below said cavity, wherein an abrupt material interface defines the whole lateral boundary of said cavity and said cavity is patterned such that it provides two dimensional lateral confinement of photon modes, said upper an lower contacts being arranged such that current can flow vertically across the cavity between the two contacts.