Hybrid beamsteerer for steering a light beam with both sub-aperture and full-aperture beam steering portions

• US 10,133,083 B1
• Filed: 08/16/2017
• Issued: 11/20/2018
• Est. Priority Date: 08/16/2017
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Ziemkiewicz, Michael, Anderson, Michael Howard, Davis, Scott Robert, Luey, Benjamin, Dunn, Tyler Adam
• Primary Examiner(s): Jordan, Andrew
• Application Number:
  US15/678,741
• Time in Patent Office: 461 Days
• Field of Search: None
• CPC Class Codes: G02B 2005/1804 Transmission gratings
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G02B 26/108 having one or more prisms as scanning elements
• CPC Class Codes: G02B 27/4233 having a diffractive element [DOE] contributing to a non-imaging application diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086
• CPC Class Codes: G02B 27/44 Grating systems; Zone plate systems G02B27/46 takes precedence
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• 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 2203/24 beam steering

Abstract

A non-mechanical beamsteerer can be provided to adjust an angle of a light beam, such as to scan the light beam over a field of regard. The non-mechanical beamsteerer can include a first collection of steering elements that are smaller than a size of a light beam. The first collection of steering elements can adjust the angle of the light beam by diffracting the light beam. The non-mechanical beamsteerer can also include a second collection of steering elements that are larger than a size of the light beam. The second collection of steering elements can adjust an angle of the light beam by refracting the light beam. The non-mechanical beamsteerer can operate without a compensation plate, such as to provide a reduced size of the beamsteerer and an increased acceptance angle of the beamsteerer.

Claims

1. A beamsteering apparatus for adjusting an angle of a light beam, the beamsteering apparatus comprising:

a first beam steering portion comprising;

a collection of sub-aperture beam steering elements to diffract the light beam in an in-plane direction; and

a second beam steering portion comprising;

a collection of full-aperture refractive beam steering elements to refract the light beam in an in-plane direction.

2. The beamsteering apparatus of claim 1, wherein the collection of sub-aperture beam steering elements comprises a first collection of sub-aperture beam steering elements to diffract the light beam in a first in-plane direction and a second collection of sub-aperture beam steering elements to diffract the light beam in a second in-plane direction;

and

wherein the collection of full-aperture refractive beam steering elements comprises a first collection of full-aperture refractive beam steering elements to refract the light beam in the first in-plane direction and a second collection of full-aperture refractive beam steering elements to refract the light beam in the second in-plane direction.

3. The beamsteering apparatus of claim 2, wherein the first in-plane direction and the second in-plane direction are angularly opposing with respect to a bisector.

4. The beamsteering apparatus of claim 2, wherein the first collection of sub-aperture beam steering elements includes a first row of sub-aperture beam steering elements, an individual one of the sub-aperture beam steering elements in the first row of sub-aperture beam steering elements having a pitch such that an angle of the sub-aperture portion of the light beam refracted by the individual one of the sub-aperture beam steering elements corresponds to an angle of a diffractive order of the first row of sub-aperture beam steering elements.

5. The beamsteering apparatus of claim 4, wherein the second collection of sub-aperture beam steering elements includes a first row of sub-aperture beam steering elements, an individual one of the sub-aperture beam steering elements in the first row of sub-aperture beam steering elements having a pitch such that an angle of the sub-aperture portion of the light beam refracted by the individual one of the sub-aperture beam steering elements corresponds to an angle of a diffractive order of the first row of sub-aperture beam steering elements.

6. The beamsteering apparatus of claim 2, wherein the first and second collection of sub-aperture beam steering elements each include at least one row of isosceles triangles, where each individual isosceles triangle is tilted such that a base of the isosceles triangle is approximately parallel to a direction of travel of a corresponding portion of the light beam to reduce compression of the corresponding portion of the light beam.

7. The beamsteering apparatus of claim 2, wherein the first collection of sub-aperture beam steering elements includes a first row of sub-aperture refractive elements having slanted surfaces arranged to provide diffractive beam steering and a reduction in a size of the light beam corresponding to each sub-aperture refractive element, and a second row of sub-aperture refractive elements having slanted surfaces arranged relative to the slanted surfaces of the first row of sub-aperture refractive elements to provide further beam steering and an increase in the size of the light beam corresponding to each sub-aperture element to compensate for the decrease in beam size caused by the first row of sub-aperture refractive elements.

8. The beamsteering apparatus of claim 2, comprising:

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

a cladding including an electro-optic material capable of an interaction with a portion of the light beam;

wherein at least one of the first or second beam steering portions comprises at least one electrode shaped and arranged to adjust an angle of the light beam in an in-plane direction by adjusting an index of refraction of the electro-optic material.

9. The beamsteering apparatus of claim 8, comprising an evanescent out-coupler to steer the light beam in an out-of-plane direction.

10. The beamsteering apparatus of claim 1, wherein the first beam steering portion provides discrete adjustment of the angle of the light beam in increments that are more coarse than an angular steering resolution provided by the second beam steering portion.

11. A method of steering a light beam with a planar waveguide, the method comprising:

discretely diffracting sub-aperture portions of the light beam in a first in-plane direction using a first beam steering portion; and

refracting the light beam in the first in-plane direction using a second beam steering portion.

12. The method of claim 11, comprising diffracting sub-aperture portions of the light beam in a second in-plane direction, and refracting the light beam in the second in-plane direction, wherein the first in-plane direction and the second in-plane direction are angularly opposing with respect to a bisector.

13. The method of claim 11, comprising refracting a sub-aperture portion of the light beam corresponding to an individual sub-aperture refractive element at an angle corresponding to an angle of a diffractive order of a first row of a first collection of sub-aperture beam steering elements.

14. The method of claim 13, comprising diffracting the light beam into one of a set of diffraction orders of the first row of the first collection of sub-aperture beam steering elements, by applying one of a set of discrete steering voltages to the first row of sub-aperture beam steering elements.

15. The method of claim 11, comprising diffracting the light beam using at least one row of tilted isosceles triangles in a first collection of sub-aperture beam steering elements, where each individual isosceles triangle is tilted such that a base of the isosceles triangle is approximately parallel to a direction of travel of a corresponding portion of the light beam to reduce compression of the corresponding portion of the light beam.

16. The method of claim 11, comprising diffractively steering the light beam in the first in-plane direction and reducing a size of the light beam corresponding to each sub-aperture refractive element in a first row of sub-aperture refractive elements, and further diffractively steering the light beam in the first in-plane direction and increasing the size of the light beam corresponding to each of the plurality of sub-aperture refractive elements to compensate for the decrease in beam size caused by the first row of sub-aperture refractive elements.

17. The method of claim 11, comprising:

guiding the light beam along a length of a waveguide; and

adjusting an angle of the light beam in an in-plane direction by adjusting an index of refraction of an electro-optic cladding interacting with a portion of the light beam.

18. The method of claim 11, wherein the first beam steering portion provides discrete adjustment of the angle of the light beam in increments that are more coarse than an angular steering resolution provided by the second beam steering portion.

19. A waveguide for adjusting an angle of a light beam, the waveguide comprising:

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

a cladding including an electro-optic material capable of an interaction with a portion of the light beam;

electrodes shaped and arranged to adjust an angle of the light beam in an in-plane direction by adjusting an index of refraction of the electro-optic material;

wherein the arrangement of electrodes includes;

a first beam steering portion comprising;

a collection of sub-aperture beam steering elements to diffract the light beam in an in-plane direction; and

a second beam steering portion comprising;

a collection of full-aperture refractive beam steering elements to refract the light beam in an in-plane direction.

20. The waveguide of claim 19, wherein the collection of sub-aperture beam steering elements includes a first row of sub-aperture beam steering elements, an individual one of the sub-aperture beam steering elements in the first row of sub-aperture beam steering elements having a pitch such that an angle of the sub-aperture portion of the light beam refracted by the individual one of the sub-aperture beam steering elements corresponds to an angle of a diffractive order of the first row of sub-aperture beam steering elements.

21. The waveguide of claim 20 wherein the collection of sub-aperture beam steering elements includes a second row of sub-aperture beam steering elements configured to further steer the light beam in the first in-plane direction, an individual one of the sub-aperture beam steering elements in the second row of sub-aperture beam steering elements having a same pitch as the individual sub-aperture beam steering elements in the first row.

22. The waveguide of claim 19, wherein the collection of sub-aperture beam steering elements includes a first row of sub-aperture beam steering elements configured to steer the light beam in a first in-plane direction, an individual one of the sub-aperture beam steering elements in the second row of sub-aperture beam steering elements having a pitch such that an angle of the sub-aperture portion of the light beam refracted by the individual one of the sub-aperture beam steering elements corresponds to an angle of a diffractive order of the first row of sub-aperture beam steering elements;

and

wherein the collection of sub-aperture beam steering elements includes a second row of sub-aperture beam steering elements configured to steer the light beam in a second in-plane direction, an individual one of the sub-aperture beam steering elements in the second row of sub-aperture beam steering elements having a pitch such that an angle of the sub-aperture portion of the light beam refracted by the individual one of the sub-aperture beam steering elements corresponds to an angle of a diffractive order of the second row of sub-aperture beam steering elements.

23. The waveguide of claim 19, wherein the first beam steering portion provides discrete adjustment of the angle of the light beam in increments that are more coarse than an angular steering resolution provided by the second beam steering portion.