Hybrid Grating Optical Phased Array for Wide-Angle LiDAR
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Solution Overview
Problem
Existing scanning type LIDARs for autonomous vehicles face challenges with mechanical rotation limitations, high power consumption, limited viewing angles, and sensitivity to temperature changes, while silicon nitride waveguides suffer from cross-talk and noise issues due to their refractive index properties.
Innovation Solution
An optical phase array antenna with a hybrid grating structure, featuring a clad layer with recessed portions and a CMOS semiconductor process, enhances directionality and reduces perturbation strength, achieving a horizontal viewing angle of 120° or more and a vertical viewing angle of 20° or more, with a maximum output of 2 W or more, by modulating light phases and optimizing waveguide configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon nitride waveguides are used to reduce laser threshold power, then laser power consumption is reduced, but cross-talk between adjacent waveguides increases due to low refractive index causing increased evanescent wave interaction
Solution Approach 1:
The patent introduces asymmetric grating structures (first and second gratings) with different configurations on the silicon nitride waveguide. This asymmetry creates directional coupling that suppresses evanescent wave interaction between adjacent waveguides while maintaining low power operation, thereby reducing cross-talk without sacrificing energy efficiency.
Solution Approach 2:
The grating structures act as intermediary elements that mediate the optical field distribution around the waveguide. These gratings control the evanescent wave propagation and prevent harmful interactions between neighboring waveguides, enabling close spacing while maintaining signal isolation.
2Adaptability or versatility
If antenna elements are spaced closer to widen horizontal viewing angle, then viewing angle increases, but desired output phase distribution is not obtained due to cross-talk between adjacent elements
Solution Approach 1:
The patent replaces mechanical phase adjustment mechanisms with optical grating-based phase control. The grating structures provide precise phase modulation through optical path difference, enabling accurate phase distribution even when antenna elements are closely spaced, thus maintaining phase precision while expanding viewing angle.
Solution Approach 2:
The patent utilizes vertical dimension by introducing grating structures that extend perpendicular to the waveguide plane. This three-dimensional grating configuration provides additional phase control degrees of freedom, enabling precise phase distribution in closely spaced antenna arrays by controlling light propagation in multiple dimensions.
3Ease of manufacture
If planar optical elements are used for manufacturing, then manufacturing simplicity is maintained, but clear spatial directionality is lost due to vertical refractive index symmetry causing similar emission ratios from upper and lower ends
Solution Approach 1:
The patent introduces asymmetric grating structures that break the vertical refractive index symmetry of planar optical elements. These gratings create preferential emission directions by modifying the optical path and phase distribution, achieving clear spatial directionality while maintaining compatibility with standard planar manufacturing processes.
4Adaptability or versatility
If mechanical rotation is used to achieve 360° viewing angle, then viewing coverage is complete, but weight and power consumption increase due to motor requirements
Solution Approach 1:
The patent replaces mechanical rotation systems with optical phase array technology. By using grating-based phase modulation and beam steering, the system achieves wide viewing angles (120° horizontal, 20° vertical) without mechanical moving parts, eliminating motor weight and associated power consumption while maintaining autonomous vehicle applicability.
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 provides a lighter, cheaper, and more efficient LIDAR system with improved directionality and reduced noise, suitable for autonomous vehicles and unmanned aerial vehicles, capable of operating effectively across a wide temperature range without mechanical rotation.
Implementation Method 1
modulating a phase of the dispersed laser
Implementation Method 2
a structure formed by changing the height of an antenna element waveguide of a light output unit and having a plurality of diffraction gratings spaced apart from each other
Data Source
AI summary
Provided is an optical phase array antenna including a coupling unit for receiving light from a light source, a light distribution unit for distributing light propagated from the coupling unit to a plurality of optical paths, a phase modulation unit for modulating a phase of the light distributed from the light distribution unit, and a light output unit that outputs the light modulated by the phase modulation unit, and includes an antenna element waveguide extending at a predetermined length through which the light propagates, and a clad layer formed to surround the antenna element waveguide, in which the antenna element waveguide has a first recessed portion recessed downward with respect to an upper surface thereof, and the clad layer has a second recessed portion recessed downward with respect to an upper surface thereof at a position adjacent to the first recessed portion.