Photonic Integrated Circuit Illumination for Display Systems
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Solution Overview
Problem
Conventional display illumination systems, particularly those using LEDs and laser beam scanning, face challenges such as low efficiency, limited color gamut, and compatibility issues with diffractive type displays. Additionally, existing laser displays have large footprints and are not suitable for reflective-type displays like LCoS, and they often have limited resolution and exit pupil size.
Innovation Solution
The use of photonic integrated circuit (PIC) illumination elements that incorporate lasers and out-coupling emitters to provide efficient and versatile laser-based illumination for various display types, including transmissive LCDs and reflective LCoS displays. These PIC illumination elements can be designed with non-aligned pixel-by-pixel arrays, allowing for easier integration and reduced complexity in display systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED illumination is used, then the display system has simple structure, but the illumination efficiency and brightness are low
Solution Approach 1:
The patent replaces conventional LED illumination with a photonic integrated circuit (PIC) system that uses laser light sources and waveguide-based light distribution. This substitution enables higher illumination efficiency through controlled light propagation in waveguides and selective out-coupling, while maintaining manageable system complexity through integration of multiple functions in a compact PIC architecture.
Solution Approach 2:
The PIC illumination element serves multiple functions: it generates light via laser sources, guides and distributes light through waveguides, controls light out-coupling at specific locations, and can be adapted to different display types (AR, VR, MR). This multi-functionality achieves high illumination efficiency without proportionally increasing system complexity.
2Illumination intensity
If laser beam scanning is used, then the color gamut is improved, but the footprint and device size increase
Solution Approach 1:
The patent transitions from spatial scanning (2D movement) to a planar waveguide-based light distribution approach. Light is guided across the display surface through integrated waveguides, enabling compact footprint while maintaining laser-based color performance. The out-coupling emitters are distributed across the waveguide surface, eliminating the need for mechanical scanning components.
Solution Approach 2:
The patent combines laser light generation, light guiding, and light distribution functions into a single integrated PIC structure. This merging eliminates separate scanning mechanisms and reduces the overall footprint while preserving the high color gamut benefits of laser illumination.
3Illumination intensity
If conventional laser displays are used, then the brightness is improved, but the compatibility with reflective-type displays is poor
Solution Approach 1:
The patent segments the illumination function into distributed out-coupling emitters along the waveguide, with each emitter illuminating a specific region of the display. This segmentation enables adaptation to different display types by adjusting the out-coupling pattern and waveguide configuration, while maintaining high brightness through laser-based illumination.
Solution Approach 2:
The patent changes the illumination parameters (light distribution pattern, coupling method, emitter arrangement) to achieve compatibility with different display types. By adjusting these parameters in the PIC system, the same hardware can serve multiple display technologies including reflective LCoS and transmissive LCD displays while maintaining high brightness.
4Manufacturing precision
If pixel-by-pixel aligned arrays are used, then the illumination precision is improved, but the integration complexity increases
Solution Approach 1:
The patent introduces the waveguide as an intermediary between the laser light source and the display surface. The waveguide mediates the light distribution, allowing out-coupling emitters to be positioned without strict pixel-by-pixel alignment requirements. This intermediary approach maintains illumination precision while significantly reducing integration complexity.
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 PIC illumination elements offer improved efficiency, higher contrast, and compatibility with different display types, while reducing the form factor and complexity of display systems. They provide well-controlled illumination with suppressed stray light scattering, enabling better performance in augmented and virtual reality applications.
Implementation Method 1
a waveguide including: a core that is transparent to one or more wavelengths of light and has a first refractive index; and a cladding surrounding the core, the cladding having a second refractive index that is different than the first refractive index
Implementation Method 2
an array of out-coupling emitters configured to emit light from the PIC illumination element toward the display element
Data Source
AI summary
A display system may include a display element having an array of pixels, at least one light source, and a photonic integrated circuit (PIC) illumination element overlapping the display element. The PIC illumination element may include at least one in-coupler for in-coupling light from the at least one light source and an array of out-coupling emitters configured to emit light from the PIC illumination element toward the display element. The array of out-coupling emitters may not be aligned pixel-by-pixel with the array of pixels. Various other devices, systems, and methods are also disclosed.