Chirped polarization volume grating for wide FOV and high‐efficiency waveguide‐based AR displays

Abstract

We demonstrate a reflective chirped polarization volume grating as a strong contender for wide field-of-view augmented reality display systems. By introducing gradient pitch along the beam propagation direction, the angular bandwidth extends dramatically from 18 to 54 while keeping over 80% average efficiency and 95% peak efficiency.

Augmented Reality and Virtual Reality Displays: Perspectives and Challenges

“…Meanwhile, the index contrast of the coupler determines the angular and spectral responses, especially for grating and hologram, which affects the color uniformity over the FOV and the eye-box ( Kress, 2019 ). Due to the significant impact of the coupler on the system, numerous technologies have been applied to optimize the coupler performance ( Xiang et al., 2018 ; Gao et al., 2017 ; Yin et al., 2019 ; Yin et al, 2020b ). As a result, the angular response of an LNED system is not limited by the coupler but by the critical angle of TIR, which is in turn determined by the lightguide refractive index.…”

“…(2017) attempted to apply the spatially multiplexing in out-coupler HVG to obtain wide FOV. Lately, LC-based polarization volume gratings (PVGs), also known as Bragg polarization gratings, with high diffraction efficiency and large angular bandwidth have been reported ( Lee et al., 2017a ; Yin et al, 2020b ). Due to these special optical features, it is feasible to build a spatially multiplexed AR system with a large FOV using PVGs.…”

Spotlighting Recent Advances in Liquid‐Crystal Devices for Beam‐Steering Applications

“…Generally, the incident angle can be ±10° while maintaining a high efficiency. For a passive PBD, if we apply a multilayer structure, the field of view can be increased dramatically to ±30° or even larger with a designed wavelength and diffraction angle 5,14 …”

“…One of the biggest advantages of PBD is its large working area. Through the interference fabrication process, PBD's clear aperture size can be larger than 2 inches, depending on the exposure beam size 5,14 …”

“…PRECISELY POSITIONING AND STEERING A LASER BEAM OR light ray has enabled widespread applications, including light detection and ranging (LiDAR) for self‐driving vehicles, 1,2 high‐resolution head‐mounted displays (HMDs), 3 eye tracking for fovea displays, 4 folding the optical path in augmented reality (AR) displays, 5 microscopy, 6 and laser micromachining 7 . Along the way, various beam‐steering methods have been developed.…”