Optical waveguide mode discriminator

Claim 2

In an optical communication system of the type wherein a plurality of dielectric waveguide modes are propagated in a single multimode optical waveguide, each mode carrying information corresponding to a separate modulation signal, a mode discriminator system comprising a plurality of optical waveguide mode discriminators, the first of which has a V value such that only the lowest order mode propagated by said multimode waveguide will propagate therein, the second of which has a V value such that only the lowest and second lowest order modes propagated by said multimode waveguide will propagate therein, and each succeeding mode discriminator has a V value higher than that of the previous mode discriminator so that it is capable of propagating one more of the modes propagated by said multimode waveguide than the immediately preceding mode discriminator, means for directing a portion of the light radiating from said multimode waveguide onto an end of each of said mode discriminators, a plurality of light detectors, one of which is disposed in light receiving relationship with respect to a corresponding one of said plurality of mode discriminators, the first detector receiving light radiating from said first mode discriminator, the second detector receiving light from said second mode discriminator, and each successive detector receiving light from the next successive mode discriminator, and means for combining in a subtracting relationship the first and second detector output signals to provide an electrical signal corresponding to the information carried by the second lowest order mode propagated by sAid multimode waveguide.

Claim 3

A system in accordance with claim 1 further comprising means for equalizing the amplitude and phase of the lowest order mode information contained in the electrical signals at the outputs of said first and second detectors.

Claim 4

A system in accordance with claim 2 wherein said means for equalizing comprises a delay line connected to the output of said first detector, the output of said delay line being connected to said means for combining.

Claim 5

A system in accordance with claim 3 wherein said means for equalizing further comprises means for amplifying the output from each of said light detectors.

Claim 6

A system in accordance with claim 2 wherein said means for equalizing comprises an optical delay line disposed between said first mode discriminator and said first light detector, and means for directing light emanating from said first mode discriminator onto said optical delay line.

Claim 7

A system in accordance with claim 1 wherein said means for directing comprises means for reflecting at least a portion of the light radiating from said multimode waveguide onto each mode discriminator.

Claim 8

In an optical communication system of the type wherein a plurality of dielectric waveguide modes are propagated in a single multimode optical waveguide, each mode carrying information corresponding to a separate modulation signal, a mode discriminator system comprising a plurality of optical waveguide mode discriminators, the first of which has a V value such that only the lowest order mode propagated by said multimode waveguide will propagate therein, the second of which has a V value such that only the lowest and second lowest order modes propagated by said multimode waveguide will propagate therein, and each succeeding mode discriminator has a V value higher than that of the previous mode discriminator so that it is capable of propagating one more of the modes propagated by said multimode waveguide than the immediately preceding mode discriminator, means for directing a portion of the light radiating from said multimode waveguide onto an end of each of said mode discriminators, a plurality of light detectors, one of which is disposed in light receiving relationship with respect to a corresponding one of said plurality of mode discriminators, the first detector receiving light radiating from said first mode discriminator, the second detector receiving light from said second mode discriminator, and each successive detector receiving light from the next successive mode discriminator, first delay means connected to the output of said first detector, and first subtracter means for subtracting the output of said first delay means from the output from said second detector to provide an electrical signal corresponding to the information carried by the second lowest order mode propagated by said multimode waveguide.

Claim 9

In an optical communication system of the type wherein a plurality of dielectric waveguide modes are propagated in a single multimode optical waveguide, each mode carrying information corresponding to a separate modulation signal, a mode discriminator system comprising a plurality of optical waveguide mode discriminators, the first of which has a V value such that only the lowest order mode propagated by said multimode waveguide will propagate therein, the second of which has a V value such that only the lowest and second lowest order modes propagated by said multimode waveguide will propagate therein, and each succeeding mode discriminator has a V value higher than that of the previous mode discriminator so that it is capable of propagating one more of the modes propagated by said multimode waveguide than the immediately preceding mode discriminator, means for directing a portion of the light radiating from said multimode waveguide onto an end of each of said mode discriminators, a plurality of light detectors, one of which is disposed in light receiving relationship with respect to a corresponding one of said plurality of mode discriminators, the first detector receiving light radiating from said first mode discriminator, the second detector receiving light from said second mode discriminator, and each successive detector receiving light from the next successive mode discriminator, first delay means connected to the output of said first detector, and first subtracter means for subtracting the output of said first delay means from the output from said second detector to provide an electrical signal corresponding to the information carried by the second lowest order mode propagated by said multimode waveguide.

Claim 10

A system in accordance with claim 7 further comprising second delay means connected to the output of said first detector, third delay means connected to the output of said first subtracter means, and second subtracter means for subtracting the outputs of said second and third delay means from the output of the third of said plurality of light detectors to provide an electrical signal corresponding to the information carried by the third lowest order mode propagated by said multimode waveguide.