Photonic Integrated Circuit Grating Couplers for Low-Divergence Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional laser-scanning displays and LiDAR systems face challenges in miniaturization and complexity due to the use of discrete optical components and MEMS mirrors, which limit resolution, field of view, and frame rate, and require complex packaging and alignment.
Innovation Solution
A photonic integrated circuit chip with a movable plate and integrated lasers, waveguides, and gratings that emit red, green, and blue light, allowing for two-dimensional scanning without collimation lenses, and can be part of a light engine or LiDAR system, utilizing actuators for tilting the movable plate to scan light across a field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional laser-scanning systems use MEMS mirrors with larger diameters to reduce beam divergence, then beam quality is improved, but the mirror frequency must be reduced which limits scanning speed and resolution
Solution Approach 1:
The patent replaces the mechanical MEMS mirror system with a photonic integrated circuit that uses optical waveguides and grating couplers to steer light. This substitution eliminates the mechanical limitations of MEMS mirrors, allowing for high-frequency operation without being constrained by mirror diameter and beam divergence trade-offs. The photonic circuit uses optical interference and diffraction at grating couplers to achieve beam steering with much smaller physical dimensions.
Solution Approach 2:
The patent changes the operating parameters by using photonic integrated circuits that can operate at significantly higher frequencies than MEMS mirrors. The grating coupler design allows for efficient light coupling at these higher frequencies, and the waveguide structure maintains beam quality without requiring large physical dimensions. This parameter change enables both high beam quality and high scanning speed simultaneously.
2Measurement precision
If conventional laser-scanning systems increase the number of lasers for multi-beam scanning to improve resolution, then resolution is improved, but device complexity and packaging difficulty increase
Solution Approach 1:
The patent merges multiple laser sources and their associated optical paths into a single photonic integrated circuit. The waveguides on the photonic circuit can carry multiple wavelengths (colors) simultaneously, and the grating couplers can direct these different wavelengths into multiple beams. This consolidation reduces the number of discrete components from many individual lasers and optics to a single integrated chip, dramatically reducing complexity while maintaining multi-beam scanning capability for high resolution.
Solution Approach 2:
The photonic integrated circuit serves multiple functions within a single device: it generates multiple wavelengths, guides them through waveguides, steers them using grating couplers, and produces multiple scanning beams. This multi-functionality replaces what would traditionally require separate components for each function, reducing overall system complexity while enabling high-resolution multi-beam scanning.
3Measurement precision
If conventional laser-scanning systems use discrete optical components to achieve high resolution, then resolution is improved, but the system size and packaging complexity increase
Solution Approach 1:
The patent implements a nested structure where waveguides are embedded within the photonic integrated circuit substrate, and grating couplers are formed by patterning the substrate itself. The entire optical system (lasers, waveguides, gratings, and beam-steering elements) is nested within a single chip footprint. This nested integration reduces the system volume from what would be required for discrete components to a compact chip-scale device while maintaining high resolution through precise optical control.
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 solution enables faster, higher-resolution scanning with smaller, lighter, and less complex systems compared to conventional laser-scanning displays and LiDAR, overcoming limitations of MEMS mirrors by using photonic integrated circuits to emit collimated beams.
Implementation Method 1
The grating is integrated with the movable plate in optical communication with the slab waveguide and emits the red, green, and blue light into free space
Implementation Method 2
the actuator is operably coupled to the movable plate and tilts the movable plate about the first and second axes so as to scan the red, green, and blue light across at least a portion of a field of view
Data Source
AI summary
Laser-scanning systems for augmented reality glasses displays and LiDAR (light detection and ranging) use photonic integrated circuits to generate multiple collimated (or low-divergence) modulated laser beams. Laser light is guided on the photonic chip, expanded, and emitted from the surface of the chip (using grating coupler devices) as one or more large-diameter (e.g., millimeter-scale), collimated or low-divergence beams. These gratings may be integrated onto movable microelectromechanical systems (MEMS) plates to steer the beam along two angular axes. Alternatively, the beam(s) from the grating(s) may be steered by a separate MEMS mirror integrated onto the photonic chip or on another chip. Such systems enable multi-beam laser scanning systems without collimation lenses, reducing the size and packaging complexity of high-performance laser scanning systems for augmented reality glasses and LiDAR.