Electro-optic beam deflector device

• US 9,885,892 B2
• Filed: 11/23/2016
• Issued: 02/06/2018
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Anderson, Michael H., Davis, Scott R., Rommel, Scott D.
• Primary Examiner(s): Jordan, Andrew
• Application Number:
  US15/360,752
• Publication Number:
  US 20170192264A1
• Time in Patent Office: 440 Days
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/291 Two-dimensional analogue deflection
• CPC Class Codes: G02F 1/295 Analog deflection from or in an optical waveguide structure]
• CPC Class Codes: G02F 1/2955 by controlled diffraction or phased-array beam steering controlled diffraction for optical waveguide switching G02F1/313
• CPC Class Codes: G02F 2201/06 integrated waveguide
• CPC Class Codes: G02F 2201/12 electrode
• CPC Class Codes: G02F 2201/122 having a particular pattern

Abstract

A substantially planar waveguide for dynamically controlling the out-of-plane angle at which a light beam exits the waveguide. Generally, liquid crystal materials may be disposed within a waveguide in a cladding proximate or adjacent to a core layer of the waveguide. In one example, the waveguide may contain one or more taper regions such that the light beam exits the waveguide and propagates out-of-the-plane of the waveguide into an out-coupling medium at a propagation angle. In one example, the waveguide may contain one or more electrodes onto which one or more voltages may be applied. The magnitude of the propagation angle may be electronically controlled by altered by controlling or altering the magnitude of the one or more applied voltages.

Claims

1. A waveguide for adjusting an angle of a light beam in an out-of-plane direction, the waveguide comprising:

a waveguide core configured to guide the light beam along a length of the waveguide;

a cladding including a liquid crystal material, the cladding being configured to provide an interaction between an evanescent portion of the light beam and the liquid crystal material and confine the light beam within the waveguide core in an out-of-plane direction in a first region of the waveguide;

an out-coupling medium configured to receive an evanescently coupled portion of the light beam at a first out-of-plane angle from the waveguide core in a second region of the waveguide; and

at least one electrode configured to adjust an angle of the light beam in an out-of-plane direction by adjusting an index of refraction of the liquid crystal material to establish the first out-of-plane angle at which the evanescently coupled portion of the light beam enters the out-coupling medium.

2. The waveguide of claim 1 wherein a thickness of the cladding decreases from a first thickness in the first region of the waveguide to a second thickness in the second region of the waveguide, the first thickness in the first region being selected to inhibit evanescent coupling between the waveguide core and the out-coupling medium, and the second thickness in the second region being selected to provide evanescent coupling between the waveguide core and the out-coupling medium.

3. The waveguide of claim 1 wherein a difference between an adjustable effective index of refraction and an index of refraction of the out-coupling medium determines the first out-of-plane angle of the evanescently out-coupled light beam.

4. The waveguide of claim 3 wherein the effective index of refraction is based on a combination of an index of refraction of the cladding and an index of refraction of the waveguide core.

5. The waveguide of claim 3 wherein the first out-of-plane angle of the evanescently out-coupled light beam is determined by an inverse sine of the adjustable effective index of refraction divided by the index of refraction of the out-coupling medium.

6. The waveguide of claim 1 wherein the out-coupling medium includes a facet configured to refract the evanescently coupled light beam at a second out-of-plane angle when exiting the out-coupling medium.

7. The waveguide of claim 1 wherein evanescently coupling the portion of the light beam at the first out-of-plane angle from the waveguide core in the second region of the waveguide provides a collimated light beam.

8. The waveguide of claim 1 wherein the thickness of the cladding decreases from a first thickness in the first region of the waveguide to a second thickness in the second region in an s-shaped taper to cause the out-coupled light beam to have a Gaussian profile.

9. A planar waveguide for adjusting an angle of a light beam in an out-of-plane direction, the planar waveguide comprising:

a waveguide core configured to direct the light beam along a length of the waveguide;

a first cladding including a liquid crystal material, the first cladding configured to confine the light beam within the waveguide core along an out-of-plane direction, the first cladding being further configured to provide an interaction between an evanescent portion of the light beam and the liquid crystal material;

a second cladding configured to confine the light beam within the waveguide core along an out-of-plane direction in a first region of the waveguide;

an out-coupling medium configured to receive an evanescently coupled portion of the light beam at a first out-of-plane angle from the waveguide core in a second region of the waveguide and transmit the evanescently coupled portion of the light beam out of the out-coupling medium at a second out-of-plane angle, wherein a thickness of the second cladding is tapered in the second region of the waveguide to provide the evanescent coupling between the waveguide core and the out-coupling medium; and

at least one electrode configured to adjust the angle of the light beam in an out-of-plane direction by adjusting an effective index of refraction to establish the first out-of-plane angle at which the evanescently coupled portion of the light beam enters the out-coupling medium.

10. The planar waveguide of claim 9 wherein a thickness of the second cladding decreases from a first thickness in the first region of the waveguide to a second thickness in the second region of the waveguide, the first thickness in the first region being selected to inhibit evanescent coupling between the waveguide core and the out-coupling medium, and the second thickness in the second region being selected to provide evanescent coupling between the waveguide core and the out-coupling medium.

11. The planar waveguide of claim 9 wherein the effective index of refraction is based on a combination of an index of refraction of the first cladding, an index of refraction of the second cladding, and an index of refraction of the waveguide core.

12. The planar waveguide of claim 11 wherein a difference between an adjustable effective index of refraction and an index of refraction of the out-coupling medium determines the first out-of-plane angle of the evanescently out-coupled light beam.

13. The planar waveguide of claim 9 wherein the liquid crystal material has a tunable index of refraction and the at least one electrode is configured to adjust the index of refraction of the liquid crystal material.

14. The planar waveguide of claim 9 wherein the out-coupling medium includes a facet configured to refract the evanescently coupled light beam at a second out-of-plane angle when exiting the out-coupling medium.

15. A planar waveguide for adjusting an angle of a light beam in an out-of-plane direction, the planar waveguide comprising:

a waveguide core configured to direct the light beam along a length of the waveguide;

a first cladding configured to confine the light beam within the waveguide core along an out-of-plane direction;

a second cladding including a liquid crystal material and configured to confine the light beam within the waveguide core along an out-of-plane direction in a first region of the waveguide, the second cladding being further configured to provide an interaction between an evanescent portion of the light beam and the liquid crystal material;

an out-coupling medium configured to receive an evanescently coupled portion of the light beam at a first out-of-plane angle from the waveguide core in a second region of the waveguide and transmit the evanescently coupled portion of the light beam out of the out-coupling medium at a second out-of-plane angle, wherein a thickness of the second cladding is tapered in the second region of the waveguide to provide the evanescent coupling between the waveguide core and the out-coupling medium; and

at least one electrode configured to adjust the angle of the light beam in an out-of-plane direction by adjusting an effective index of refraction to establish the first out-of-plane angle at which the evanescently coupled portion of the light beam enters the out-coupling medium.

16. The planar waveguide of claim 15 wherein a thickness of the second cladding decreases from a first thickness in the first region of the waveguide to a second thickness in the second region of the waveguide, the first thickness in the first region being selected to inhibit evanescent coupling between the waveguide core and the out-coupling medium, and the second thickness in the second region being selected to provide evanescent coupling between the waveguide core and the out-coupling medium.

17. The planar waveguide of claim 15 wherein the effective index of refraction is based on a combination of an index of refraction of the first cladding, an index of refraction of the second cladding, and an index of refraction of the waveguide core.

18. The planar waveguide of claim 17 wherein a difference between an adjustable effective index of refraction and an index of refraction of the out-coupling medium determines the first out-of-plane angle of the evanescently out-coupled light beam.

19. The planar waveguide of claim 15 wherein the liquid crystal material has a tunable index of refraction and the at least one electrode is configured to adjust the index of refraction of the liquid crystal material.

20. The planar waveguide of claim 15 wherein the out-coupling medium includes a facet configured to refract the evanescently coupled light beam at a second out-of-plane angle when exiting the out-coupling medium.

21. A method for adjusting an angle of a light beam in an out-of-plane direction, the method comprising:

guiding the light beam along a length of a waveguide;

providing an interaction between an evanescent portion of the light beam and a liquid-crystal material and confining the light beam within a waveguide core and a cladding in an out- of-plane direction in a first region of the waveguide;

receiving, by an out-coupling medium, an evanescently out-coupled portion of the light beam at a first out-of-plane angle from the waveguide core and the cladding in a second region of the waveguide; and

adjusting an angle of the light beam in an out-of-plane direction by adjusting an index of refraction of the liquid crystal material in the second region of the waveguide to establish the first out-of-plane angle at which the evanescently coupled portion of the light beam enters the out-coupling medium.

22. The method of claim 21 further comprising providing a decreasing thickness of the cladding from a first thickness in the first region of the waveguide to a second thickness in the second region of the waveguide to, the first thickness in the first region being selected to inhibit evanescent coupling between the waveguide core and the out-coupling medium, and the second thickness in the second region being selected to provide evanescent coupling between the waveguide core and the out-coupling medium.

23. The method of claim 21 further comprising determining the first out-of-plane angle of the evanescently out-coupled light beam from a difference between an adjustable effective index of refraction and an index of refraction of the out-coupling medium.

24. The method of claim 23 further comprising determining the effective index of refraction from a combination of an index of refraction of the cladding and an index of refraction of the waveguide core.

25. The method of claim 21 further comprising refracting the evanescently out-coupled light beam at a second out-of-plane angle when exiting the out-coupling medium.

26. The method of claim 23 further comprising determining the first out-of-plane angle of the evanescently out-coupled light beam from an inverse sine of the adjustable effective index of refraction divided by the index of refraction of the out-coupling medium.

27. The method of claim 21 further comprising providing a collimated light beam from the evanescently coupled portion of the light beam from the waveguide core at the first out-of-plane angle in the second region of the waveguide.

28. The method of claim 21 further comprising providing a decreasing thickness of the cladding from a first thickness in the first region of the waveguide to a second thickness in the second region in an s-shaped taper to cause the out-coupled light beam to have a Gaussian profile.