Optical Phased Array Antenna With MEMS Mirror for Wide-FOV LiDAR
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Solution Overview
Problem
Existing scanning-type lidars are heavy, power-consuming, and unsuitable for unmanned aerial vehicles due to mechanical rotation limitations, and they face challenges with high laser output, limited horizontal field of view, and phase variation due to temperature changes.
Innovation Solution
The development of an optical phased array antenna with a tapered waveguide for a lidar, utilizing a CMOS process to achieve a compact size, high light transmittance, and low return loss, along with an MEMS mirror for vertical scan, to enhance the horizontal field of view and scan speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a mechanical motor rotation system is used to achieve 360° field of view, then the field of view coverage is improved, but the weight and power consumption increase significantly
Solution Approach 1:
The patent replaces the mechanical motor rotation system with an optical phased array antenna that uses optical path modulation to change beam direction. Instead of physically rotating the lidar sensor, the system modulates the phase of light waves to electronically steer the laser beam across different angles, achieving wide field of view coverage without mechanical moving parts, thereby significantly reducing weight and power consumption.
Solution Approach 2:
The patent changes the control parameter from mechanical rotation angle to optical phase modulation. By adjusting the phase difference of light waves emitted from different antenna elements, the system can dynamically control the direction of the laser beam without any physical movement. This parameter transformation enables rapid beam steering and eliminates the need for heavy mechanical rotors.
2Area of stationary object
If antenna elements are placed close together to increase horizontal field of view, then the field of view is improved, but cross-talk between elements increases and phase distribution deteriorates
Solution Approach 1:
The patent applies different structural characteristics to different parts of the antenna array. Specifically, it uses waveguides with varying cross-sectional areas or different waveguide structures at different positions within the array. This local differentiation allows adjacent waveguides to have different optical characteristics, reducing mutual interference and cross-talk while maintaining close spacing for wide field of view coverage.
Solution Approach 2:
The patent segments the antenna array into multiple independent or semi-independent waveguide channels, each with optimized local characteristics. By dividing the array into distinct segments with controlled coupling between them, the system can maintain tight spacing for wide coverage while managing cross-talk through proper segmentation and isolation of adjacent elements.
3Ease of manufacture
If a flat optical element with vertical refractive index symmetry is used, then the manufacturing is simplified, but the space directionality of discharged signals is poor
Solution Approach 1:
The patent introduces asymmetry in the optical path structure by using waveguides with different cross-sectional areas or different propagation characteristics at different positions. This asymmetric design breaks the vertical refractive index symmetry, creating distinct optical path differences between signals discharged at different locations. The asymmetry enables better spatial directionality and separation of signals while still being manufacturable using standard semiconductor processes.
4Power
If signals are discharged from both upper and lower ends of the chip, then the light output is maximized, but interference and noise increase due to reflections
Solution Approach 1:
The patent extracts or removes the problematic reflection interface by designing the optical system to prevent signal discharge at the lower end of the chip, or by eliminating the reflective interface at that location. Instead of having signals discharge from both upper and lower ends, the system is configured to discharge signals only from the upper end, thereby eliminating the source of reflected interference and noise while maintaining sufficient light output through optimized waveguide design.
Solution Approach 2:
The patent converts the potential harm of reflections into a benefit by using anti-reflection coatings or impedance matching structures at the discharge interfaces. These treatments minimize unwanted reflections by matching the impedance between the waveguide and the external medium, thereby reducing interference noise while maintaining high light output efficiency.
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 proposed solution enables a lightweight, cost-effective lidar with a 120° horizontal field of view and 100 kHz scan speed, suitable for autonomous and unmanned aerial vehicles, while maintaining high signal transmittance and reduced noise.
Implementation Method 1
an antenna element waveguide to which the output light or the reflective light propagates and that extends a predetermined length, wherein antenna element waveguide is formed such a width of a first end connected to the phase modulator is different from a width of a second end from which the output light is output or to which the reflective light is input
Data Source
AI summary
Disclosed is an optical phased array antenna for a lidar that outputs output light provided from a light source to a measurement object and that receives reflective light reflecting from the measurement object, the optical phased array antenna including: a combiner configured to receive output light output from the light source or to output the reflective light; a phase modulation module configured to modulate a phase of the output light input from the combiner or the reflective light that is transmitted to the combiner; and an optical input/output unit configured to output the output light modulated by the phase modulation module or receive the reflective light reflecting from the measurement object and configured to have an antenna element waveguide to which the output light or the reflective light propagates and that extends a predetermined length.