Magneto-photonic crystal isolators

1. A magneto-optical isolator for an optical circuit, the isolator comprising:

a substrate; and

an optical channel disposed next to the substrate, the optical channel and substrate being configured to transmit optical radiation within the optical channel, the optical channel including a photonic-crystal rotator, the rotator having at least one defect and including a magnetic material, and wherein the optical channel includes a series of depressions having a periodicity and wherein the defect includes a variation in the periodicity of the depressions.

2. An isolator as set forth in claim 1 wherein the isolator further comprises first and second polarizers.

3. An isolator as set forth in claim 1 and further comprising a magnet having a magnetic field, the magnet being positioned such that the field interacts with the rotator.

4. An isolator as set forth in claim 1 wherein the substrate, the optical channel, and the rotator form a monolithic photonic device.

5. An isolator as set forth in claim 1 wherein the optical channel is a magnetic material.

6. An isolator as set forth in claim 5 wherein the magnetic material is selected from the group consisting of yttrium iron garnet (YIG), bismuth-substituted YIG, bismuth-substituted dysprosium iron garnet, and cerium-substituted YIG.

7. A photonic-crystal rotator for an optical isolator, the rotator comprising:

a substrate; and

an optical channel disposed next to the substrate, the optical channel and substrate being configured to transmit optical radiation within the optical channel, the optical channel including a magneto-photonic band-gap material having a defect;

wherein the optical channel has an axis,

wherein the optical channel includes a series of depressions along the axis, the series of depressions having a periodicity, and

wherein the defect includes a variation in the periodicity of the depressions.

8. A rotator as set forth in claim 7 wherein the variation in the periodicity is a lack of at least one depression.

9. A rotator as set forth in claim 7 wherein the depressions are holes within the optical channel.

10. A rotator as set forth in claim 9 wherein the variation in the periodicity is a lack of at least one hole.

11. A rotator as set forth in claim 7 wherein the optical channel includes a series of grates along the axis,

wherein the depressions are formed by the grates.

12. A photonic-crystal rotator for an optical isolator, the rotator comprising:

a substrate; and

an optical channel disposed next to the substrate, the optical channel and substrate being configured to transmit optical radiation within the optical channel, the optical channel including a magneto-photonic band-gap material having a defect, wherein the optical channel has an axis,

wherein the optical channel includes a series of grates along the axis, the series of grates having a periodicity, and

wherein the defect includes a variation in the periodicity of the grates.

13. A rotator as set forth in claim 12 wherein each grate has a length in the direction of the axis, and

wherein the variation in the periodicity is a variation in the length of at least one of the grates.

14. A photonic-crystal rotator for an optical isolator, the rotator comprising:

a substrate; and

an optical channel disposed next to the substrate, the optical channel and substrate being configured to transmit optical radiation within the optical channel, the optical channel including a magneto-photonic band-gap material having a defect, wherein the optical channel has an axis,

wherein the optical channel includes a slab and a ridge disposed on the slab, the ridge being in a direction of the axis,

wherein the ridge includes a series of depressions along the axis, the series of depressions having a periodicity, and

wherein the defect includes a variation in the periodicity of the depressions.

15. A rotator as set forth in claim 14 wherein the slab and the ridge are unitary.

16. A photonic-crystal rotator for an optical isolator, the rotator comprising:

a substrate; and

an optical channel disposed next to the substrate, the optical channel and substrate being configured to transmit optical radiation within the optical channel, the optical channel including a magneto-photonic band-gap material having a defect, wherein the optical channel has an axis,

wherein the optical channel includes a slab and a ridge disposed on the slab, the ridge being in a direction of the axis,

wherein the optical channel further includes a series of grates disposed on the ridge along the axis, the series of grate having a periodicity, and

wherein the defect includes a variation in the periodicity of the grates.

17. A rotator as set forth in claim 16 wherein the slab, the ridge, and the grates are unitary.