Waveguide for AR glasses
SRG (Surface Relief Grating) Waveguide
SRG waveguides control the direction of light by creating a fine, uneven structure called a grating on the surface of the waveguide.For AR glasses applications, they are typically composed of three types of gratings: an in-coupling grating, expanding grating, and out-coupling grating.
In all grating designs, a high refractive index material can be deposited and processed onto a substrate such as high refractive index glass or resin to give each grating functionality and properties suitable for AR glasses.
Titanium dioxide (TiO2) is used as the high refractive index material for deposition, and processing shapes include Line and Space, and Staircase shapes. Furthermore, high-end products are being developed that utilize silicon carbide (SiC), which has an even higher refractive index, as the substrate, and feature a structure where the SiC substrate itself is processed.
TiO2Line and Space gratings on a glass substrate
TiO2Line and Space gratings on a glass substrate
