Multiple core optical waveguide for secure transmission

Claim 2

A glass optical waveguide comprising: a primary core having a first index of refraction: a plurality of other cores having axes parallel to and outside of said primary core, said other cores having a different index of refraction than said first index, the index of refraction of at least two adjacent other cores being the same; and a common cladding surrounding all of said cores, the index of refraction of each core being greater than the index of refraction of said cladding.

Claim 3

The glass optical waveguide recited in claim 1 in a communication system for detecting intrusion upon said optical waveguide comprising: means for propagating and detecting light signals along said optical waveguide; and means for detecting a change in said relative light loss between said primary core and said other cores to identify perturbation of said waveguide.

Claim 4

The system recited in claim 2 wherein said means for propagating light signals includes means for applying different wavelengths of light to different ones of said other cores and wherein said means for detecting includes means for detecting a change in said relative light loss between said primary and secondary cores at different wavelengths.

Claim 5

The system recited in claim 2 wherein said means for propagating includes means for propagating light in said other cores having a longer wavelength than the light propagated in said primary cores.

Claim 6

The optical waveguide recited in claim 1 wherein the index of refraction of said primary core is substantially greater than the index of refraction of said other cores.

Claim 7

The optical waveguide recited in claim 1 wherein said other cores have a diameter which is substantially greater than the diameter of said primary core.

Claim 8

The waveguide recited in claim 1 wherein the relative index difference between said other cores and said cladding ##EQU7## is substantially less than the index difference ##EQU8## where n 1 is the index of refraction of said first core, n 2 is the index of refraction of said other cores and n 3 is the index of refraction of said cladding.

Claim 9

A multiple core optical waveguide comprising: at least primary and secondary glass cores having parallel separated axes and a common cladding, the index of refraction of all cores being greater than the index of refraction of said cladding and the index of refraction of said primary core being substantially greater than the index of refraction of said secondary core, the relative index difference between said secondary core and said cladding, ##EQU9## being substantially less than the index difference ##EQU10## where n 1 is the index of refraction of said primary core, n 2 is the index of refraction of said secondary core, and n 3 is the index of refraction of said cladding.

Claim 10

A multiple core optical waveguide comprising: at least primary and secondary glass cores having parallel separated axes and a common cladding, the index of refraction of all cores being greater than the index of refraction of said cladding and the index of refraction of said primary core being substantially greater than the index of refraction of said secondary core, the relative index difference between said secondary core and said cladding, ##EQU9## being substantially less than the index difference ##EQU10## where n 1 is the index of refraction of said primary core, n 2 is the index of refraction of said secondary core, and n 3 is the index of refraction of said cladding.

Claim 11

The apparatus recited in claim 8 wherein said primary core is coaxial with said cladding and a plurality of secondary cores are disposed around said primary core.

Claim 12

The apparatus recited in claim 8 wherein said optical waveguide cores have a decreasing refractive index profile with distance from the axis.

Claim 13

Apparatus for detecting intrusion upon an optical waveguide communication system comprising: a glass optical waveguide having multiple cores and cladding, the index of refraction of each core being greater than the index of refraction of its cladding, the relative light loss between a primary core and a secondary core being much different upon perturbation of the waveguide because of a substantial difference in at least one of the following: the relative core cladding index difference, wherein the index of refraction of said primary core is substantially greater than the index of refraction of said secondary core, wavelengths of light transmitted in the cores, and diameters of said primary and secondary cores; means for propagating and detecting light signals along said optical waveguide; and means for detecting a change in said relative light loss between said primary and secondary cores to identify perturbation of said optical fiber.

Claim 14

Apparatus for detecting intrusion upon an optical waveguide communication system comprising: a glass optical waveguide having multiple cores and cladding, the index of refraction of each core being greater than the index of refraction of its cladding, the relative light loss between a primary core and a secondary core being much different upon perturbation of the waveguide because of a substantial difference in at least one of the following: the relative core cladding index difference, wherein the index of refraction of said primary core is substantially greater than the index of refraction of said secondary core, wavelengths of light transmitted in the cores, and diameters of said primary and secondary cores; means for propagating and detecting light signals along said optical waveguide; and means for detecting a change in said relative light loss between said primary and secondary cores to identify perturbation of said optical fiber.

Claim 15

The apparatus recited in claim 11 wherein said primary and secondary cores have parallel separated axes within the same cladding.

Claim 16

The apparatus recited in claim 12 wherein said primary core is coaxial with said cladding and a plurality of secondary cores are disposed around said first core.

Claim 17

The apparatus recited in claim 11 wherein said primary core has a substantially smaller diameter than said secondary core.

Claim 18

The apparatus recited in claim 11 wherein each core sustains a single mode of propagation.

Claim 19

The apparatus recited in claim 11 wherein each core sustains multiple modes of propagation.

Claim 20

The apparatus recited in claim 11 wherein said primary and secondary cores are coaxial.

Claim 21

The apparatus recited in claim 11 wherein said optical waveguide cores have a decreasing refractive index profile with distance from the axis of said cores.

Claim 22

The apparatus recited in claim 11 wherein said primary and secondary cores are coaxial rings of different refractive index glass.

Claim 23

The apparatus recited in claim 11 wherein the relative index difference between said secondary core and said cladding ##EQU11## is substantially less than the index difference ##EQU12## where n 1 is the index of refraction of said primary core, n 2 is the index of refraction of said secondary core and n 3 is the index of refraction of said cladding.

Claim 24

The apparatus recited in claim 11 wherein the relative index difference between said secondary core and said cladding ##EQU13## is substantially less than the index difference ##EQU14## where n 1 is the index of refraction of said primary core, n 2 is the index of refraction of said secondary core and n 3 is the index of refraction of said cladding.