Abstract: 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.

Abstract: A semiconductor device comprising a vertical stack of layers, comprising: an active layer configured to support a two dimensional carrier gas having an excess of carriers; source and drain contacts provided to said active layer such that a current can flow between said source and drain contacts through said two dimensional carrier gas; a lower conducting region, wherein said lower contact conducting region is a patterned lower conducting region such that said active layer is suspended across gaps in said lower conducting region and said active layer is physically supported by and suspended between parts of said lower conducting region.