Mixed Grating Waveguide for Diffraction Display Light Efficiency
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Solution Overview
Problem
Conventional optical waveguide devices for diffraction displays based on two-dimensional gratings suffer from low light coupling efficiency and non-uniformity of the outgoing light field, limiting their brightness and image quality.
Innovation Solution
An optical waveguide device incorporating a combination of one-dimensional and two-dimensional gratings, where the coupling-out grating features a one-dimensional region and a two-dimensional region, with the one-dimensional region located further away from the main propagation direction than the two-dimensional region, allowing for improved light utilization and coupling efficiency through total reflection and diffraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two-dimensional coupling-out grating is used, then the device can expand light two-dimensionally and couple light out, but the propagation efficiency and coupling-out efficiency are low
Solution Approach 1:
The coupling-out grating is segmented into multiple diffraction units with different grating vector directions. Each unit directs light at specific angles, allowing selective coupling out of certain diffraction orders while maintaining total internal reflection for others. This segmentation enables high coupling-out efficiency for desired orders while preserving propagation efficiency through the waveguide.
Solution Approach 2:
Different regions of the coupling-out grating are assigned different local properties: some areas have gratings oriented to couple out specific diffraction orders, while other areas are designed to maintain total internal reflection. This local differentiation allows the grating to simultaneously achieve high coupling efficiency for selected orders and maintain low loss for the waveguide propagation path.
2Ease of operation
If a two-dimensional coupling-out grating is used, then light can be coupled out, but the uniformity of the outgoing light field is poor
Solution Approach 1:
The coupling-out grating is divided into multiple diffraction units, each responsible for coupling out light at specific angles and positions. This segmentation allows precise control over the spatial distribution of outgoing light, enabling uniform illumination across the exit pupil by appropriately designing the grating vectors and periods of each unit.
Solution Approach 2:
The grating parameters (vector directions, periods, and orientations) are systematically varied across different diffraction units to achieve uniform light distribution. By carefully adjusting these parameters, the patent optimizes the outgoing light field uniformity while maintaining high coupling efficiency for multiple diffraction orders.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mixed grating structure enhances light coupling efficiency and uniformity of the outgoing light field, enabling better image brightness and quality in diffraction-based displays.
Implementation Method 1
the coupling-in grating is configured to couple an input light beam from outside of the waveguide substrate into the waveguide substrate so that the input light beam is transmitted to the coupling-out grating through total reflection
Implementation Method 2
the coupling-out grating comprises a one-dimensional region in which a one-dimensional grating is formed and a two-dimensional region in which a two-dimensional grating is formed
Data Source
AI summary
The present application discloses an optical waveguide device, which comprises a waveguide substrate and a coupling-in grating and a coupling-out grating arranged on the waveguide substrate, and the coupling-in grating is configured to couple an input light beam from the outside of the waveguide substrate into the waveguide substrate so that the input light beam can be transmitted to the coupling-out grating through total reflection. Wherein the coupling-in grating has a grating vector direction pointing to the coupling-out grating, and the coupling-out grating includes a one-dimensional region in which a one-dimensional grating is formed and a two-dimensional region in which a two-dimensional grating is formed. The application further discloses display equipment comprising the optical waveguide device.