Optical switches including a ring resonator

1 . A structure for an optical switch, the structure comprising:

a first waveguide core including a first portion and a second portion;

a second waveguide core including a first portion and a second portion; a ring resonator having a first portion adjacent to the first portion of the first waveguide core and a second portion adjacent to the first portion of the second waveguide core, the first portion of the ring resonator spaced from the first portion of the first waveguide core by a first gap over a first light coupling region, and the second portion of the ring resonator spaced from the first portion of the second waveguide core by a second gap over a second light coupling region;

an optical coupler coupled to the second portion of the first waveguide core and the second portion of the second waveguide core;

a first phase shifter associated with the first portion of the first waveguide core, the first phase shifter arranged between the ring resonator and the optical coupler; and

a second phase shifter associated with the first portion of the second waveguide core, the second phase shifter arranged between the ring resonator and the optical coupler.

2 . The structure of claim 1 wherein the first phase shifter is a thermo-optic phase shifter that includes a first resistive heating element and a second resistive heating element.

3 . The structure of claim 2 wherein the second phase shifter is a thermo-optic phase shifter that includes a first resistive heating element and a second resistive heating element.

4 . The structure of claim 1 wherein the second portion of the first waveguide core is disposed between the first portion of the first waveguide core and the optical coupler.

5 . The structure of claim 4 wherein the second portion of the second waveguide core is disposed between the first portion of the second waveguide core and the optical coupler.

6 . The structure of claim 5 wherein the second portion of the second waveguide core is longer than the second portion of the first waveguide core.

7 . The structure of claim 1 wherein the optical coupler is a directional coupler that includes a third portion of the first waveguide core and a third portion of the second waveguide core adjacent to the third portion of the first waveguide core.

8 . The structure of claim 1 wherein the optical coupler is a multimode interference coupler that includes a first input coupled to the second portion of the first waveguide core and a second input coupled to the second portion of the second waveguide core.

9 . The structure of claim 1 wherein the first gap is constant over the first light coupling region, and the second gap is constant over the second light coupling region.

10 . The structure of claim 1 wherein the ring resonator is a third waveguide core with an oblong shape having a first side section and a second side section, the first portion of the ring resonator includes the first side section of the third waveguide core, and the second portion of the ring resonator includes the first side section of the third waveguide core.

11 . The structure of claim 10 wherein the first gap has a first width that is constant between the first side section and the first portion of the first waveguide core over the first light coupling region, and the second gap has a second width that is constant between the second side section and the first portion of the second waveguide core over the second light coupling region.

12 . The structure of claim 1 further comprising:

a semiconductor substrate; and

a dielectric layer on the semiconductor substrate,

wherein the first waveguide core, the second waveguide core, the ring resonator, and the optical coupler are disposed on the dielectric layer.

13 . The structure of claim 1 wherein the second portion of the second waveguide core includes a bend having a curvature configured to route the second waveguide core away from the first waveguide core, and the bend has a curvature of about 180°.

14 . The structure of claim 13 wherein the second portion of the second waveguide core and the second portion of the first waveguide core have equal lengths.

15 . The structure of claim 13 further comprising:

a terminator,

wherein the first waveguide core includes a portion upstream from the ring resonator defining an input port for directing light to the structure, and the second waveguide core includes an open end that is coupled to the terminator.

16 . A structure for an optical switch, the structure comprising:

a first waveguide core including a first portion and a second portion;

a second waveguide core including a first portion and a second portion;

a first ring resonator disposed adjacent to the first portion of the first waveguide core;

a second ring resonator disposed between the first ring resonator and the first portion of the second waveguide core;

an optical coupler coupled to the second portion of the first waveguide core and the second portion of the second waveguide core;

a first phase shifter associated with the first portion of the first waveguide core, the first phase shifter arranged between the first and second ring resonators and the optical coupler; and

a second phase shifter associated with the first portion of the second waveguide core, the second phase shifter arranged between the first and second ring resonators and the optical coupler.

17 . The structure of claim 16 wherein the second portion of the second waveguide core includes a bend having a curvature configured to route the second waveguide core away from the first waveguide core, and the bend has a curvature of about 180°.

18 . The structure of claim 17 further comprising:

a terminator,

wherein the first waveguide core includes a portion upstream from the first ring resonator defining an input port for directing light to the structure, and the second waveguide core includes an open end that is coupled to the terminator.

19 . A method of forming a structure for an optical switch, the method comprising:

forming a first waveguide core that includes a first portion and a second portion;

forming a second waveguide core that includes a first portion and a second portion;

forming a ring resonator having a first portion adjacent to the first portion of the first waveguide core and a second portion adjacent to the first portion of the second waveguide core, wherein the first portion of the ring resonator is spaced from the first portion of the first waveguide core by a first gap over a first coupling region, and the second portion of the ring resonator is spaced from the first portion of the second waveguide core by a second gap over a second coupling region;

forming an optical coupler that is coupled to the second portion of the first waveguide core and the second portion of the second waveguide core;

forming a first phase shifter associated with the first portion of the first waveguide core, wherein the first phase shifter is arranged between the ring resonator and the optical coupler; and

forming a second phase shifter associated with the first portion of the second waveguide core, wherein the second phase shifter arranged between the ring resonator and the optical coupler.

20 . The method of claim 19 wherein the second portion of the second waveguide core includes a bend having a curvature configured to route the second waveguide core away from the first waveguide core, the bend has a curvature of about 180°, the first waveguide core includes a portion upstream from the ring resonator defining an input port for directing light to the structure, and the second waveguide core includes an open end that is coupled to a terminator.