Theoretical efficiency limit of diffractive input couplers in augmented reality waveguides

Area of Science:

• Optics and Photonics
• Materials Science
• Computer Science

Background:

• Augmented reality (AR) displays require efficient waveguide combiners for immersive wearable experiences.
• Transparent waveguide combiners are crucial for AR glasses, guiding light while maintaining see-through capability.
• Achieving high efficiency and image quality in waveguide combiners is essential for realistic AR.

Purpose of the Study:

• To develop a theoretical model for calculating the upper bound of input efficiency in diffractive waveguide combiners.
• To identify fundamental efficiency limits of input couplers, constrained by physical principles.
• To explore the impact of polarization management and geometric parameters on input efficiency.

Main Methods:

• Introduced a theoretical model based on Lorentz reciprocity and energy conservation.
• Incorporated polarization management for arbitrary input polarization states.
• Analyzed the influence of waveguide thickness, projector pupil size, and relief distance on efficiency.

Main Results:

• Determined the theoretical upper bound for input efficiency in uniform gratings.
• Quantified the impact of polarization control on enhancing input efficiency.
• Showcased how geometric parameters affect the achievable input efficiency.

Conclusions:

• The theoretical model provides a deterministic approach to optimize input coupler efficiency.
• Polarization control is a key factor in overcoming efficiency limitations in diffractive waveguide combiners.
• Understanding these fundamental limits guides the design of more efficient AR waveguide displays.