Optical waveguide beam splitter with plural partial extraction features for display

1. An optical device, comprising:

a spatial light modulator; and

an optical waveguide with a plurality of extraction features positioned relative to the optical waveguide so that a respective extraction feature:

receives light, having propagated within the optical waveguide, in a first direction; and

directs a first portion of the light in a second direction distinct from the first direction to exit the optical waveguide and illuminate at least a portion of the spatial light modulator and direct a second portion, distinct from the first portion, of the light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide.

2. The optical device of claim 1 , wherein:

the respective extraction feature is selected from a group consisting of a surface relief grating, a holographic optical element, a volume Bragg grating, or a Fresnel prism.

3. The optical device of claim 1 , wherein:

the plurality of extraction features is embedded inside the optical waveguide.

4. The optical device of claim 1 , wherein:

the plurality of extraction features is disposed adjacent to a surface of the optical waveguide.

5. The optical device of claim 1 , wherein:

the plurality of extraction features defines a plane that is parallel to a surface of the optical waveguide.

6. The optical device of claim 1 , wherein:

the plurality of extraction features includes a first extraction feature and a second extraction feature;

the first extraction feature receives first light, directs a first portion of the first light in the second direction to exit the optical waveguide, and directs a second portion of the first light to undergo total internal thereby continuing to propagate within the optical waveguide as second light, wherein a ratio between the first portion and the second portion of the first light has a first value; and

the second extraction feature receives the second light, directs a first portion of the second light in the second direction to exit the optical waveguide, and directs a second portion of the second light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide, wherein a ratio between the first portion and the second portion of the second light has a second value distinct from the first value.

7. The optical device of claim 6 , wherein:

the plurality of extraction features includes a third extraction feature positioned so that the second extraction feature is positioned between the first extraction feature and the third extraction feature; and

the third extraction feature receives the second portion of the second light as third light, directs a first portion of the third light in the second direction to exit the optical waveguide, and directs a second portion of the third light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide, wherein a ratio between the first portion and the second portion of the third light has a third value distinct from the second value.

8. The optical device of claim 7 , wherein:

the third value corresponds to the first value, and the second value is greater than the first value and the third value.

9. The optical device of claim 6 , wherein the first portion of the first light is received by a first region of the spatial light modulator and the first portion of the second light is received by a second region distinct from the first region of the spatial light modulator.

10. The optical device of claim 9 , wherein the first portion of the first light has a first intensity when incident on the first region, the first portion of the second light has a second intensity when incident on the second region, and the second intensity corresponds to the first intensity.

11. The optical device of claim 9 , wherein:

the first extraction feature and the second extraction feature are configured to receive image light from the spatial light modulator in a third direction and transmit at least a portion of the image light.

12. The optical device of claim 11 , wherein:

the optical waveguide includes a first surface and an opposing second surface;

the spatial light modulator is optically coupled with the first surface; and

the optical device also includes a polarizer disposed adjacent to the second surface of the optical waveguide, the polarizer configured to:

receive the image light transmitted through the optical waveguide; and

transmit at least a portion of the image light, the transmitted portion having a particular polarization.

13. The optical device of claim 6 , wherein:

the respective extraction feature is a switchable grating that is switchable between different states, including a first state and a second state distinct from the first state;

the first state causes the respective extraction feature to direct the first portion of the light in the second direction to exit the optical waveguide and direct the second portion of the light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide; and

the second state causes the respective extraction feature to transmit the received light such that the received light undergoes total internal reflection, thereby continuing to propagate within the optical waveguide.

14. The optical device of claim 13 , wherein:

the first state causes the first portion of the light to illuminate a respective region of the spatial light modulator; and

the second state causes the respective extraction feature to forgo illuminating the respective region of the spatial light modulator.

15. The optical device of claim 1 , wherein:

the respective extraction feature is polarization selective.

16. The optical device of claim 1 , further including a first retarder plate disposed inside the optical waveguide.

17. A head-mounted display device comprising the optical device of claim 1 .

18. A method for providing illumination light, the method comprising:

receiving light, having propagated within an optical waveguide, in a first direction with a respective extraction feature of a plurality of extraction features optically coupled with the optical waveguide;

directing, with the respective extraction feature, a first portion of the light in a second direction to exit the optical waveguide and directing a second portion, distinct from the first portion, of the light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide; and

illuminating at least a portion of a spatial light modulator with the first portion of the light.

19. The method of claim 18 , wherein:

the respective extraction feature is selected from a group consisting of a surface relief grating, a holographic optical element, a volume Bragg grating, or a Fresnel prism.

20. The method of claim 18 , further including:

receiving first light with a first extraction feature of the plurality of extraction features, directing a first portion of the first light in the second direction to exit the optical waveguide, and directing a second portion of the first light to undergo total internal thereby continuing to propagate within the optical waveguide as second light, wherein a ratio between the first portion and the second portion of the first light has a first value; and

receiving the second light with a second extraction feature of the plurality of extraction features, directing a first portion of the second light in the second direction to exit the optical waveguide, and directing a second portion of the second light to undergo total internal reflection, thereby continuing to propagate within the optical waveguide, wherein a ratio between the first portion and the second portion of the second light has a second value distinct from the first value.