Prism-free fabrication of multiplexed holographic waveguide couplers for full-color near-eye displays

Full-color holographic waveguide couplers are required in advanced augmented reality (AR) near-eye display (NED) technologies due to their superior light manipulation capabilities. However, the traditional fabrication process relies on prisms to fabricate the holographic grating structures, posing significant challenges for large-scale manufacturing. The present work addresses this issue by proposing a prism-free fabrication design for full-color waveguide couplers. Our technique utilizes wavelength shifting and multiplexing of volume holographic gratings (VHGs) with three sequential exposures on a single film. The theoretical analysis, validated by optical simulations, demonstrates flexibility in selecting propagation angles that successfully transmit the correct color spectra for each color-specific grating through the waveguide. The experimental verification, which involves the fabrication of multiplexed VHGs, demonstrates the capability of reproducing true colors, thereby making waveguides based on this technology suitable for full-color AR NEDs, which could meet the current requirements of commercial companies in healthcare, gaming, and manufacturing.