Optical switch and matrix optical switch

• US 7,302,140 B2
• Filed: 04/05/2006
• Issued: 11/27/2007
• Est. Priority Date: 08/20/2004
• Status: Expired due to Fees

• Current Assignee: EpiPhotonics Corp.
• Original Assignee: KEIO University
• Inventors: Nashimoto, Keiichi
• Primary Examiner(s): Font; Frank G.
• Assistant Examiner(s): LEPISTO, RYAN A
• Application Number:
  US11/398,151
• Publication Number:
  US 20060257073A1
• Time in Patent Office: 601 Days
• Field of Search: 385/9, 385/43, 385/45
• US Class Current: 385/43
• CPC Class Codes: G02B 2006/12145 Switch
• CPC Class Codes: G02B 2006/1215 Splitter
• CPC Class Codes: G02F 1/3137 with intersecting or branching waveguides, e.g. X-switches and Y-junctions
• CPC Class Codes: G02F 1/315 based on the use of controlled internal reflection

Abstract

The invention provides an optical switch including a substrate which has conductivity or semiconductivity, an optical waveguide layer which is formed on the substrate, and a control electrode which is formed on the optical waveguide layer. The optical waveguide layer includes an incident-side channel waveguide to which a light signal is incident and plural outgoing-side channel waveguides branched from the incident-side channel waveguide. The control electrode forms a reflection plane reflecting the incident light signal near a crossover portion of the plural outgoing-side channel waveguides by applying voltage to the optical waveguide layer with the substrate to control a refractive index of the optical waveguide layer, and switches propagation paths of the light signal.

Claims

1. An optical switch comprising:

a substrate which has at least partial conductivity;

an optical waveguide layer which is formed on the substrate, the optical waveguide layer including an incident-side channel waveguide, having a centerline and an outgoing side, on which a light signal is incident and a plurality of outgoing-side channel waveguides, each having a centerline and an incident side, and branching from the incident-side channel waveguide; and

a control electrode having a waveguide side which is formed on a crossover portion of the plurality of the outgoing-side channel waveguides of the optical waveguide layer, the control electrode forming, near the crossover portion of the plurality of outgoing-side channel waveguides, a reflection plane which reflects the incident light signal by applying a voltage to the optical waveguide layer to control the refractive index of the optical waveguide layer, and the control electrode switches propagation paths of the light signal,

wherein a taper portion which broadens out in the propagation direction of the light signal is formed on the outgoing side of the incident-side channel waveguide, and the taper portion is connected to the incident side of the plurality of the outgoing-side channel waveguides through a coupling portion,

wherein a reverse taper portion which narrows in the propagation direction of the light signal is formed on the incident side of the plurality of the outgoing-side channel waveguides.

2. An optical switch according to claim 1, wherein a grooved portion is formed between adjacent outgoing-side channel waveguides in the optical waveguide layer.

3. An optical switch according to claim 2,

wherein the reflection plane being contiguous to an interface between the optical waveguide layer and the grooved portion, and the control electrode switches propagation paths of the light signal.

4. An optical switch according to claim 1, wherein the substrate has semiconductivity.

5. An optical switch according to claim 1, wherein the control electrode is formed on the optical waveguide layer so that an angle formed by a centerline of the incident-side channel waveguide and an edge on a waveguide-side of the control electrode is equal to an angle formed by a centerline of the outgoing-side channel waveguide and the edge on the waveguide-side of the control electrode.

6. An optical switch according to claim 1, wherein an angle formed by two centerlines of adjacent outgoing-side channel waveguides is within the range from 0.5°

to 2.0°

.

7. An optical switch according to claim 1, wherein the coupling portion is formed by a linear channel waveguide having the same width as the taper portion formed on the outgoing side end of the incident-side channel waveguide.

8. An optical switch according to claim 1, wherein a taper length of the taper portion is within the range from 200 μ

m to 2000 μ

m.

9. An optical switch according to claim 1, wherein the maximum width of the taper portion is within the range from 5 μ

m to 50 μ

m.

10. An optical switch according to claim 1, wherein a taper length of the reverse taper portion is within the range from 200 μ

m to 2000 μ

m.

11. An optical switch according to claim 1, wherein the maximum width of the reverse taper portion is within the range from 5 μ

m to 50 μ

m.

12. An optical switch according to claim 1, wherein the substrate includes a single crystal substrate portion, and the optical waveguide layer comprises an electro-optic oxide substance.

13. An optical switch according to claim 12, wherein the single crystal substrate portion has at least partial conductivity.

14. An optical switch according to claim 13, wherein the single crystal substrate portion includes SrTiO₃ doped with impurity elements.

15. An optical switch according to claim 12, wherein the substrate has a thin film at least having partial conductivity provided on a surface of the single crystal substrate portion.

16. An optical switch according to claim 15, wherein the thin film has semiconductivity.

17. An optical switch according to claim 15, wherein the single crystal substrate portion comprises Si and has an oxide buffer layer on the surface.

18. An optical switch according to claim 15, wherein the thin film is an epitaxial thin film.

19. An optical switch according to claim 15, wherein the thin film is a thin film having a single orientation.

20. An optical switch according to claim 12, wherein the optical waveguide layer comprises an epitaxial electro-optic oxide substance.

21. An optical switch according to claim 12, wherein the optical waveguide layer comprises an electro-optic oxide substance having a single orientation.

22. An optical switch according to claim 12, wherein a buffer layer having a refractive index smaller than that of the optical waveguide layer is provided between the substrate and the optical waveguide layer.

23. An optical switch according to claim 22, wherein the buffer layer comprises an epitaxial oxide.

24. An optical switch according to claim 22, wherein the buffer layer comprises an oxide having a single orientation.

25. An optical switch according to claim 22, wherein the buffer layer comprises Pb_1-xLa_x(Zr_yTi_1-y)_1-x/4O₃ (0<

x<

0.3 and 0<

x<

1.0).

26. An optical switch according to claim 12, wherein a cladding layer comprising an oxide which has a refractive index smaller than that of the optical waveguide layer is provided between the optical waveguide layer and the control electrode.

27. An optical switch according to claim 26, wherein the cladding layer comprises Pb_1-xLa_x(Zr_yTi_1-y)_1-x/4O₃ (0<

x<

0.3 and 0<

x<

1.0).

28. An optical switch according to claim 12, wherein the optical waveguide layer comprises Pb_1-xLa_x(Zr_yTi_1-y)_1-x/4O₃ (0<

x<

0.3 and 0<

y<

1.0).

29. An optical switch according to claim 1, wherein the incident-side channel waveguide and the outgoing-side channel waveguides are embedded channel waveguides.

30. An optical switch according to claim 1, wherein the incident-side channel waveguide and the outgoing-side channel waveguides are ridge channel waveguides.

31. A matrix optical switch comprising:

a substrate which has at least partial conductivity; and

a plurality of optical switch units which are arranged in a matrix on the substrate,

wherein each of the plurality of optical switch units includes

an optical waveguide layer which is formed on the substrate, the optical waveguide layer including an incident-side channel waveguide, having a centerline and an outgoing side, on which a light signal is incident and a plurality of outgoing-side channel waveguides, each having a centerline and an incident side, and branching from the incident-side channel waveguide; and

a control electrode having a waveguide side which is formed on a crossover portion of the plurality of the outgoing-side channel waveguides of the optical waveguide layer, the control electrode forming, near the crossover portion of the plurality of outgoing-side channel waveguides, a reflection plane which reflects the incident light signal by applying a voltage to the optical waveguide layer to control the refractive index of the optical waveguide layer, and the control electrode switches propagation paths of the light signal,

wherein a taper portion which broadens out in the propagation direction of the light signal is formed on the outgoing side of the incident-side channel waveguide, and the taper portion is connected to the incident side of the plurality of the outgoing-side channel waveguides through a coupling portion,

wherein a reverse taper portion which narrows in the propagation direction of the light signal is formed on the incident side of the plurality of the outgoing-side channel waveguides.

32. A matrix optical switch according to claim 31, wherein the substrate has semiconductivity.

33. A matrix optical switch comprising:

a substrate which has at least partial conductivity; and

a plurality of optical switch units which are arranged in a matrix on the substrate,

wherein each of the plurality of optical switch units includes

an optical waveguide layer which is formed on the substrate, the optical waveguide layer including an incident-side channel waveguide, having a centerline and an outgoing side, on which a light signal is incident and a plurality of outgoing-side channel waveguides, each having a centerline and an incident side, and branching from the incident-side channel waveguide, the optical waveguide layer having a grooved portion formed between adjacent outgoing-side channel waveguides, and

a control electrode having a waveguide side which is formed on a crossover portion of the plurality of the outgoing-side channel waveguides of the optical waveguide layer, the control electrode forming, near the crossover portion of the plurality of outgoing-side channel waveguides, a reflection plane reflecting the incident light signal by applying a voltage to the optical waveguide layer to control the refractive index of the optical waveguide layer, the reflection plane being contiguous to an interface between the optical waveguide layer and the grooved portion, and the control electrode switches propagation paths of the light signal,

wherein a taper portion which broadens out in the propagation direction of the light signal is formed on the outgoing side of the incident-side channel waveguide, and the taper portion is connected to the incident side of the plurality of the outgoing-side channel waveguides through a coupling portion,

wherein a reverse taper portion which narrows in the propagation direction of the light signal is formed on the incident side of the plurality of the outgoing-side channel waveguides.

34. A matrix optical switch according to claim 33, wherein the substrate has semiconductivity.