Out-of-plane computer-generated multicolor waveguide holography
Various examples of out-of-plane multicolor waveguide holography systems, methods of manufacture, and methods of use are described herein. In some examples, a multicolor waveguide holography system includes a planar waveguide to convey optical radiation between a grating coupler and a metasurface hologram. The grating coupler may be configured to couple out-of-plane optical radiation of three different color incident at three different angles into the planar waveguide. The combined multicolor optical radiation may be conveyed by the waveguide to the metasurface hologram. The metasurface hologram may diffractively decouple the three colors of optical radiation for off-plane propagation to form a multicolor holographic image in free space.
1. A dynamically reconfigurable multicolor waveguide holography system, comprising:
a multicolor light source to transmit multiple distinct colors of optical radiation at different angles;
a grating coupler to couple each of the distinct colors of optical radiation into a waveguide, wherein each color of optical radiation is incident on the grating coupler at a different angle of incidence;
a waveguide coplanar with the grating coupler to convey each color of the optical radiation from the grating coupler to a metasurface hologram with a distinct spatial frequency;
a dynamically reconfigurable metasurface hologram comprising a two-dimensional array of active subwavelength elements tunable between at least two states with different optical properties, wherein the metasurface hologram is coplanar with the grating coupler and the waveguide to decouple the distinct colors of optical radiation for off-plane propagation to form a target multicolor image as a hologram in free space; and
a controller to:
calculate a holographic pattern corresponding to the target multicolor holographic image, and
modify the dynamically reconfigurable metasurface hologram by tuning the active subwavelength elements to approximate the calculated holographic pattern.
2. The system of claim 1 , wherein the waveguide comprises a layer of electron beam resist deposited on a dielectric cladding layer.
3. The system of claim 2 , wherein the electron beam resist comprises ZEP520A.
4. The system of claim 1 , wherein the multicolor light source is configured to transmit red, green, and blue light at different angles relative to the grating coupler.
5. The system of claim 1 , wherein the waveguide is configured to convey the fundamental propagation guide mode of the optical radiation at each of the distinct colors of optical radiation.
6. The system of claim 1 , wherein the grating coupler has a grating period based on calculated propagation constants of the waveguide for each of the distinct colors of optical radiation.
7. The system of claim 6 , wherein the grating period is calculated to satisfy a phase-matching equation that is a function of the calculated propagation constants of the waveguide for each of the distinct colors of optical radiation.
8. The system of claim 1 , wherein the grating coupler is configured to couple only negative first-order waves of each of the distinct colors of optical radiation.