Waveguide-Based Augmented Reality Displays

Augmented reality (AR) has become pervasive, blending virtual content with real-world scenes. Waveguide-based AR displays have emerged as a critical technology for wearable AR systems, enabling lightweight, slim form factors and high optical performance. Waveguide combiners, which function as light guides, fold the optical path and replicate luminosity from a small light source across an expansive area through exit pupil expansion (EPE). There are three types of waveguide combiners: geometric, diffractive, and holographic.

Waveguide combiners are typically used with light engines, such as liquid-crystal-on-silicon, micro-LED, micro-OLED, laser beam scan, and MEMS. Designing waveguide combiners is challenging, considering optical performance, manufacturability, and cost factors. Challenges include EPE scheme design, field of view expansion, front geometry design of couplers, full-color displays, optical efficiency, and uniformity optimization.

While geometric waveguide combiners offer a large field of view, good uniformity, and high efficiency, they have a complicated fabrication process and low yield. Diffractive waveguide combiners have low efficiency and a smaller field of view but face issues like color nonuniformity, eye glow, and rainbow effect.

Advancements in EPE designs, fabrication methods, and materials performance of diffractive couplers could enhance diffractive waveguide combiners. PVGs and metasurface-based couplers offer dynamic modulation capabilities and design freedoms, with further advances expected to enhance their performance for Waveguide-based AR displays.

Read more

Related Content: Micro-LEDs For Ultra-Realistic Immersive Displays