Patent ID: 7915604

Claim:
An optical device comprising: a photon generator configured to generate pulses of n photons, where n can be controlled and is an integer of at least 1, at a photon generation portion; and a photon directing device configured to direct photons generated by said photon generator in a predetermined direction, said photon directing device comprising a three dimensional cavity for confining a photon such that the photon can only occupy a discrete number of optical modes in three dimensions, the three dimensional cavity being formed within a layer or a plurality of layers, confinement in at least one lateral dimension within the plane of the layer or layers being provided by a pattern of reflective interfaces, the three dimensional cavity being formed at an irregularity in the pattern, the photon generation portion being located within the three dimensional cavity or directly above or below the three dimensional cavity; wherein confinement perpendicular to the plane of the layer or layers is provided by mirror regions located on either side of said layer or layers to define a one dimensional optical cavity; and wherein at least one of the mirror regions comprises a Bragg reflector having a stack of alternating layers, said photon generator comprises a quantum dot and a pulsed laser configured to irradiate said quantum dot with a laser pulse which has a duration which is less than the relaxation time of a carrier excited by the laser pulse in said quantum dot, and the three dimensional cavity has an optical response to a second photon that changes in response to an interaction of a first photon with the quantum dot.