Ultrathin aluminosilicate glass AS 87 eco, has been produced by SCHOTT proprietary downdraw hot-forming method as thin as 50 μm. A tight thickness tolerance of ± 10um, with a TTV <10 um across an area of 400×500mm, and a surface roughness smaller than 1 nm have been achieved in mass production. Compared with other ultrathin glass, the uniqueness of AS 87 eco lies in its the outstanding chemical strengthening performance, where the surface compressive stress can reach over 800 MPa after an ion-exchange process in molten KNO3 salt bath. The high alumina content also accelerates the Na-K diffusion, and an ion exchange depth of 20 μm can be achieved after toughening at 390C for 2h. Combining such chemical strengthening with fine edge treatment results in an extremely high bending strength over 1GPa, allowing a safe bending radius as low as 3mm for 70 μm thick glass. As such, this ultrathin glass enables a highly scratch-resistant glass cover for applications such as foldable displays and any other applications requiring the combined properties of strength, transparency, flexibility, and scratch-resistance properties. Low breakage strength is the most significant obstacle for a wide application of ultrathin glass, and aluminosilicate glass can be strengthened well after ion exchange. SCHOTT is the first supplier in mass production of directly hot-formed ultrathin aluminosilicate glass eliminating the need for chemical thinning.

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Nanoimprinting of surface-relief grating-based waveguides has the potential to result in the best performing Augmented Reality (AR) smart glasses, but there are still many challenges in the design, scaling, and reproducibility of these imprinted waveguides. We presented a promising path toward mass manufacturing of optical waveguide combiners via large-area nanoimprinting at SPIE AR/VR/MR 2022. This alternative route for manufacturing surface-relief gratings on a larger area generated much interest.This follow-up paper presents a further optimized design based on the lessons learned from the previous paper, with a particular focus on quality. The complete value chain with partners is involved throughout the process of this iterative update: from design, mastering, and materials to imprinting and metrology, to prove that this method improves not only the manufacturing throughput but also the waveguide quality. We demonstrate that both the replication and image quality is true to the intended design using large area, high refractive index (1.9 RI), square (300 x 300mm) glass substrates with high refractive index resins (1.9 RI). Our objective is to further establish this new approach towards high-volume and low-cost manufacturing of waveguides based on surface relief gratings as a viable path forward for enabling the Metaverse.

Glasses are homogeneous, many glasses have excellent dielectric properties at GHz frequencies and some have thermal expansions (CTE) which are close to silicon. Ultrathin glasses (UTG) with thicknesses of 25 μm to 200 μm (0.001 to 0.0079 inch) offer numerous options for packaging, integration and co-processing in semiconductor manufacturing processes. We introduce SCHOTT UTG including paths to further improve their mechanical stability and strength. We use laser ablation in 50μm thick glass and show via fabrication with a potential of mass manufacturing with via diameters of 30μm, 38μm pitch and a position accuracy of +/− 1μm. The structures are metallized using sputtering and electroplating which leads to hermetic, tight conducting through glass-vias (TGV).

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Planar high‐refractive‐index glass wafers are the backbone of leading Augmented and Mixed Reality devices. They route the virtual image to the user's eye, while helping to keep the form factor small. While the glass characteristics directly affect fundamental design parameters such as field of view, the optical system of the wafer with its interfaces as a whole determines the image quality. Here we report on latest achievements both on the glass and on the wafer level that allow for significant weight reduction without sacrificing optical performance. Based on a state‐of‐the‐ art two layer device with a refractive index of 1.9, an overall weight reduction >20% is feasible. This creates a basis to drive AR devices from niche applications toward more widespread commercial adoption.

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