In this work we propose several full-color metagrating solutions for single waveguide-based
Augmented and Virtual Reality near-eye display systems. The presented solutions are based on a combination of
reflective and/or transmissive diffraction gratings inside or outside a waveguide. The proposed in-coupler
designs have high diffraction efficiency across a wide angular range. Applying our new grating combination
solution, we can provide good gathering of diffracted rays for the different colors. We demonstrate that by using
a dual-mode symmetrical in-coupling system and angular pupil tiling, we can extend the overall horizontal FoV
for three RGB colors. The new characteristics of the full single waveguide system including Eye Pupil Expander
and out-coupling components compatible with the proposed in-coupling solutions are discussed. We show that a
new nonsymmetrical design of metagratings can be used to change its diffraction properties improving the
diffraction efficiency and diffraction uniformity of the optical components.
“Metagrating solutions for full color single-plate waveguide combiner” Oksana Shramkova * , Valter Drazic, Guillaume Bourcin, Bobin Varghese, Laurent Blondé, and Valérie Allié , Metamaterials for Novel Wave Phenomena in Microwaves, Optics, and Mechanics. 2022.
Waveguide based optical combiners for augmented reality (AR) glasses are integrating several surface relief gratings (SRG) whose pitch sizes can be as small as 200 nm for the blue wavelength. All SRG components exploit the first diffraction order to couple in and out or to deviate the light. We present SRG using higher diffraction orders featuring over-wavelength pitch sizes. Our gratings use the edge wave (EW) diffraction phenomenon to steer light in the
preferred far field direction.
“Over-wavelength pitch sized diffraction gratings for augmented reality applications .“, Drazic, Valter; Shramkova, Oksana; Varghese, Bobin; Blondé, Laurent; De La Perrière, Vincent Brac; Schiffler, Jesse; Twardowski, Patrice; Lecler, Sylvain; Walter, Benjamin; Mairiaux, Estelle; Bavedila, Fuanki; Faucher, Marc; Allié, Valérie. 2022 Optics Express 30(2) 1293-1303
In this work we propose a new type of metagrating solution based on a combination of two diffraction gratings embedded inside the waveguide. We demonstrate that the proposed design has high intensity across a wide angular range and can be used as single waveguide full color combiner for AR application.
“Full color waveguide combiner with embedded metagrating.“, O. Shramkova, L. Blondé, V. Drazic, B. Varghese, V. Allié, 15th International Congress on Artificial Materials for Novel Wave Phenomena – Metamaterial 2021, New-York, USA.
In this work we propose a new type of symmetrical surface relief diffractive grating for waveguide-based Augmented Reality near-eye display system with a wide Field of View (FoV). We demonstrate that by using a dual-mode symmetrical in-coupling system and angular pupil tiling, we can extend the overall horizontal FoV. Our grating coupler is optimized for the second diffraction orders. The proposed concept is validated numerically via full-wave electromagnetic analysis of a 1D diffraction grating. Measurements of the diffraction efficiency of the micro-fabricated prototype are compared with the results of the numerical simulation
“High-uniformity dielectric U-shaped surface relief grating coupler for AR headsets.“, O. Shramkova, V. Drazic, B. Varghese, L. Blondé, V. Brac De La Perriere, V. Allié, SPIE Nanoscience and Engineering, 2021, San Diego, USA.
There are multiple challenges to realize waveguide-based Surface Relief Gratings (SRG) for combiners in Augmented Reality (AR) applications: fabricability, efficiency and diffraction uniformity are among the most important ones. Interdigital develops SRG using Edge Waves (EW) to design highly efficient gratings with a high angular robustness. An EW is generated by a diffraction phenomenon appearing at the interface between two dielectric media and its direction of propagation is controlled by the index ratio between the two media and the direction of the incident plane wave. Combining different edges together, we optimize the elementary geometry, i.e., the building block of an SRG, to diffract into the direction defined by the grating equation, optimizing the power transfer of the incident light into the direction of interest. Our approach enables symmetrical structures with low aspect-ratio, optimized for coupling very efficiently into the first or second order modes, the latter leads to over-wavelength pitch sizes. Moreover, our SRG is designed to angularly tile the exit pupil of the light engine without losses, making our structures adapted to any sort of light engines. Based on our unique design concept, we present in-couplers using two waveguides with a field of view of 130 degrees and RGB operation, and a one waveguide system with 90 degrees of field of view and RGB operation, both with a wafer having also an index of refraction of about 1.7. We believe this will pave the way to new DOE combiners for future AR glasses.
“High-uniformity, high-performance double material dielectric diffractive metagratings.“, Valter Drazic , Oksana Shramkova, Bobin Varghese, Laurent Blondé, Valérie Allié, 1SPIE Photonics West, Augmented, Virtual and Mixed Reality (AR, VR, MR) II, March 2021, San Francisco, USA.
In this work we propose a solution for the creation of a nanojet focusing component based on a combination of two dielectric materials capable of managing the position of the focused beam in the near zone. We demonstrate that the double-material design of the elements of metagratings can be used to change its diffraction properties improving the diffraction efficiency and diffraction uniformity.
“High-uniformity, high-performance double material dielectric diffractive metagratings.“, O. Shramkova, V. Drazic, L. Blondé, B. Varghese, V. Allié, 14th International Congress on Artificial Materials for Novel Wave Phenomena – Metamaterial 2020, New-York, USA.