Optical waveguide system and electronic device
An optical waveguide system and an electronic device are disclosed. The system comprises: a waveguide; an input coupler coupling a light into the waveguide; and an output coupler, wherein the input coupler includes a right portion and a left portion, wherein the right portion includes stacked first and second polarization volume gratings, the left portion includes stacked third and fourth polarization volume gratings. The first and fourth polarization volume gratings are polarization volume gratings optimized for a right-hand-side field of view of the light, and the third and second polarization volume gratings are polarization volume gratings optimized for a left-hand-side field of view of the light.
1. An optical waveguide system, comprising
a waveguide;
an input coupler, provided at an input side of the waveguide and coupling a light into the waveguide; and
an output coupler, provided at an output side of the waveguide and coupling the light out of the waveguide,
wherein the input coupler includes a right portion and a left portion,
wherein the right portion is located at the right side of the input coupler and the left portion is located at the left side of the input coupler, from light incident direction,
wherein the right portion includes a first polarization volume grating and a second polarization volume grating stacked under the first polarization volume grating,
wherein the left portion includes a third polarization volume grating and a fourth polarization volume grating stacked under the third polarization volume grating,
wherein, from the light incident direction, the first polarization volume grating and the second polarization volume grating, are located at the right of the third polarization volume grating and the fourth polarization volume grating,
wherein the first polarization volume grating and the fourth polarization volume grating are polarization volume gratings optimized for a right-hand-side field of view of the light, and
wherein the third polarization volume grating and the second polarization volume grating are polarization volume gratings optimized for a left-hand-side field of view of the light, and
wherein the first polarization volume grating and the fourth polarization volume grating each have a first un-symmetric field of view with a right portion thereof larger than a left portion thereof, wherein the third polarization volume grating and the second polarization volume grating each have a second un-symmetric field of view with a left portion thereof larger than a right portion thereof.
2. The optical waveguide system according to claim 1 ,
wherein
the field of views of the first polarization volume grating and the fourth polarization volume grating are (−30°, 10°),
wherein the field of views of the third polarization volume grating and the second polarization volume grating are (−10°, 30°).
3. The optical waveguide system according to claim 1 , further comprising
a central polarization volume grating, which is provided between the right portion and left portion and which is optimized for central field of view.
4. The optical waveguide system according to claim 3 , wherein
the central polarization volume grating has a symmetric field of view overlapping at least part of the field of views of the first, second, third and fourth polarization volume gratings.
5. The optical waveguide system according to claim 4 , wherein
the field of view of the central polarization volume grating is (−15°, 15°).
6. The optical waveguide system according to claim 1 , wherein
the output coupler includes a two dimensional surface relief grating.
7. The optical waveguide system according to claim 1 , wherein
the first, second, third and fourth polarization volume gratings are transmissive polarization volume gratings.
8. The optical waveguide system according to claim 1 , further comprising
a polarizer, provided before the input coupler for converting the light into a polarized light to be diffracted by the output coupler.
9. The optical waveguide system according to claim 1 , wherein
the first and third polarization volume gratings are made by liquid crystal polymers in a first liquid crystal layer,
wherein the second and fourth polarization volume gratings are made by liquid crystal polymers in a second liquid crystal layer,
wherein the first liquid crystal layer and the second liquid crystal layer have a period variation along grating plane, and different grating vectors and/or a different period localization.
10. An electronic device, comprising
a display, which generates an image light; and
an optical waveguide system according to claim 1 , which receives the image light.