Holographic optical fiber coupler

Claim 1

An optical system comprising two arrays of optical devices, and means for making individual and simultaneous optical connections each of which involves the passage of light between each selected device of one array and one selected device of the other array to the exclusion of unselected devices, said means comprising at least one phase grating plate in which there are formed a series of volume phase gratings by incidence of complementary reference beams on a holographic medium at different angles, all the phase gratings being of the reflecting type, and the arrangement being such that said individual connections are respectively made via different phase gratings in at least one phase grating plate.

Claim 7

A method of making a phase grating plate for a first form of optical system comprising arranging in relatively fixed positions two arrays of optical devices and a body of a material capable of forming a volume phase grating, and forming in said body in turn a series of volume phase gratings corresponding respectively to the required individual optical connections between each selected device in one array and one specific device in the other array to the exclusion of unspecified devices, each phase grating being formed by causing a beam of coherent light to pass between the relevant two devices in the two arrays, the beam passing first in one sense through said body and then being reflected to pass in the opposite sense through said body, whereby the passage of the incident and reflected beams produces in the body an interference pattern which is recorded by the body to form a volume phase grating of the reflecting type.

Claim 8

A method of making a phase grating plate for a first form of optical system comprising arranging in relatively fixed positions two arrays of optical devices and a body of a material capable of forming a volume phase grating, and forming in said body in turn a series of volume phase gratings corresponding respectively to the required individual optical connections between each selected device in one array and one specific device in the other array to the exclusion of unspecified devices, each phase grating being formed by causing a beam of coherent light to pass between the relevant two devices in the two arrays, the beam passing first in one sense through said body and then being reflected to pass in the opposite sense through said body, whereby the passage of the incident and reflected beams produces in the body an interference pattern which is recorded by the body to form a volume phase grating of the reflecting type.