Multiplexed Coherent Optical Phased Array LiDAR
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Solution Overview
Problem
Long-range LiDAR systems face challenges in achieving high resolution point clouds due to long time of flight for light pulses, limited integration time, and two-photon effects that reduce signal-to-noise ratio and maximum range, making it difficult to generate a sufficient number of points per second and scale output power effectively.
Innovation Solution
A novel wavelength multiplexing LiDAR scheme using multiple simultaneous wavelengths, generated by multiple lasers or a frequency comb device, is employed to increase integration time and effective power transmission, allowing for higher range distances and relaxing requirements on scanning lasers by spreading power across the optical spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single wavelength LiDAR is used, then system simplicity is maintained, but integration time is limited and two-photon effects reduce signal-to-noise ratio
Solution Approach 1:
The patent segments the optical spectrum into multiple discrete wavelengths, with each wavelength serving as an independent detection channel. This segmentation allows the system to distribute optical power across multiple wavelengths, reducing the power at each individual wavelength and thereby minimizing two-photon absorption effects while maintaining cumulative signal strength for improved signal-to-noise ratio.
Solution Approach 2:
The patent transitions from single-wavelength detection to multi-wavelength detection by adding the spectral dimension to the detection space. By encoding spatial information across multiple wavelengths, the system effectively increases the detection dimensionality, allowing simultaneous measurement of multiple spatial points with extended integration time and reduced nonlinear optical effects.
2Length of moving object
If output power is increased to extend range, then maximum range distance improves, but two-photon effects increase and reduce signal-to-noise ratio
Solution Approach 1:
The patent segments the total optical power across multiple wavelengths, so that while the cumulative power remains high for extended range, the power at each individual wavelength is reduced below the threshold where two-photon absorption becomes dominant. This segmentation strategy maintains signal strength for long-range detection while avoiding nonlinear optical effects that would degrade signal quality.
3Measurement precision
If integration time is extended to improve detection sensitivity, then signal-to-noise ratio improves, but time of flight increases and points per second decrease
Solution Approach 1:
The patent segments the detection process into multiple parallel wavelength channels, each capable of independent detection. This allows the system to perform multiple simultaneous measurements across different wavelengths, effectively multiplying the points per second output while maintaining extended integration time for each wavelength channel, thus improving both detection sensitivity and productivity.
Solution Approach 2:
The patent implements continuous wavelength multiplexing where multiple wavelengths are transmitted and detected simultaneously in parallel channels. This continuous multi-channel operation eliminates idle time between measurements, maintaining productive output while allowing each channel sufficient integration time for high sensitivity detection.
4Reliability
If multiple wavelengths are used to reduce two-photon effects, then signal-to-noise ratio and range improve, but device complexity increases
Solution Approach 1:
The patent employs a universal optical detection platform that processes multiple wavelengths through a unified detection architecture. The same photodetector and signal processing electronics are used across all wavelength channels, with wavelength discrimination achieved through optical filtering or spectral encoding. This multi-functional approach enables reliable multi-wavelength operation without proportionally increasing device 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
This approach enables higher range distances, increased dwell time on target points, and reduced two-photon effects, allowing for higher effective power transmission without lossy effects, thus improving the ability to generate accurate point clouds and extend the range of LiDAR systems.
Implementation Method 1
an optical phase array (OPA) integrated circuit (IC) device to scan the FoV using the different wavelengths
Implementation Method 2
Multiplexing and demultiplexing of the beams can be performed using waveguides and micro-resonance rings (MRRs)
Data Source
AI summary
Method and apparatus for enhancing resolution in a light detection and ranging (LiDAR) system. In some embodiments, an emitter emits light in the form of multiplexed beams of randomized, multiple wavelengths across a field of view (FoV). A detector uses one or more detection channels to detect the multiplexed beams reflected from a target within the FoV to decode range information associated with the target. The multiplexed beams may be generated by multiple light sources such as laser diodes, or a single source such as a frequency comb device. Randomization may be applied via a pseudorandom bit sequence modulator, and multiplexing/demultiplexing may be performed using waveguides and micro-resonance rings (MRRs). The multiplexed beam may be emitted using an optical phase array (OPA) integrated circuit device to scan the FoV simultaneously using the different wavelengths. The range information can be used to adaptively adjust the wavelengths in a subsequent scan.