Optical integrated circuits, semiconductor devices including the same, and methods of manufacturing the same

1. An optical integrated circuit, comprising:

a substrate including a single crystalline semiconductor material;

a passive element extending in a <100> crystal orientation of the substrate and including the single crystalline semiconductor material; and

an active element extending in a <110> crystal orientation of the substrate and including the single crystalline semiconductor material.

2. The optical integrated circuit of claim 1 , wherein the passive element includes an optical waveguide, and

wherein the active element includes a phase shifter connected to the optical waveguide.

3. The optical integrated circuit of claim 2 , wherein the optical waveguide includes:

a first core including the single crystalline semiconductor material and extending in the <100> crystal orientation of the substrate; and

a first cladding having a refractive index lower than that of the first core and surrounding the first core;

and wherein the phase shifter includes,

a second core, including the single crystalline semiconductor material and extending in the <110> crystal orientation, connected to the first core;

a second cladding having a refractive index lower than that of the second core and surrounding the second core; and

an electrode electrically connected to the second core.

4. The optical integrated circuit of claim 2 , wherein the passive element further includes an optical coupler connected to the optical waveguide.

5. The optical integrated circuit of claim 2 , wherein the optical waveguide includes first and second waveguides, and

wherein the first waveguide is connected to the phase shifter.

6. The optical integrated circuit of claim 1 , wherein the substrate is a (100) silicon wafer or a (110) silicon wafer.

7. An optical integrated circuit, comprising:

a substrate including a single crystalline semiconductor material;

a passive element extending on the substrate in a first direction parallel to a top surface of the substrate; and

an active element extending on the substrate in a second direction making an acute angle with the first direction;

wherein the passive element is configured so that light passes through the passive element in the first direction,

wherein the first direction is parallel to a <100> crystal orientation of the substrate, and

wherein the second direction is parallel to a <110> crystal orientation of the substrate.

8. The optical integrated circuit of claim 7 , wherein the passive element includes an optical waveguide, including:

a first core including the single crystalline semiconductor material and extending in the first direction; and

a first cladding having a refractive index lower than that of the first core and surrounding the first core;

and wherein the active element includes a phase shifter, including,

a second core, including the single crystalline semiconductor material and extending in the second direction, connected to the first core;

a second cladding having a refractive index lower than that of the second core and surrounding the second core; and

an electrode electrically connected to the second core.

9. An optical integrated circuit, comprising:

a substrate having a <100> crystal orientation and a <110> crystal orientation;

a passive element extending in the <100> crystal orientation and including a single crystalline semiconductor material; and

an active element extending in the <110> crystal orientation and including the single crystalline semiconductor material;

wherein the passive element is configured so that light passes through the passive element in a direction in which the passive element extends.

10. The optical integrated circuit of claim 9 , wherein the passive element includes an optical waveguide.

11. The optical integrated circuit of claim 9 , wherein the passive element includes an optical coupler.

12. The optical integrated circuit of claim 9 , wherein the passive element includes an interferometer.

13. The optical integrated circuit of claim 9 , wherein the active element includes a phase shifter.

14. The optical integrated circuit of claim 9 , wherein the passive element includes an optical waveguide, and

wherein the passive element further includes an optical coupler connected to the optical waveguide.

15. The optical integrated circuit of claim 9 , wherein the passive element includes an optical waveguide, and

wherein the active element includes a phase shifter connected to the optical waveguide.

16. The optical integrated circuit of claim 9 , wherein the passive element includes an optical waveguide,

wherein the passive element further includes an optical coupler connected to the optical waveguide, and

wherein the active element includes a phase shifter connected to the optical waveguide.

17. The optical integrated circuit of claim 9 , wherein the passive element includes a first optical waveguide, a second optical waveguide, and a first coupler, and

wherein the first optical waveguide, second optical waveguide, and first coupler meet at an interferometer.

18. The optical integrated circuit of claim 9 , wherein the passive element includes a first optical waveguide, a second optical waveguide, and a first coupler,

wherein the active element includes a phase shifter connected to the optical waveguide, and

wherein the first optical waveguide, second optical waveguide, and first coupler meet at an interferometer.

19. The optical integrated circuit of claim 9 , wherein the passive element includes a first optical waveguide, a second optical waveguide, a first coupler, and a second coupler,

wherein the first optical waveguide, second optical waveguide, and first coupler meet at a first interferometer, and

wherein the first optical waveguide, second optical waveguide, and second coupler meet at a second interferometer.