Phased Array LIDAR Using CW Laser Modulation
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Solution Overview
Problem
Conventional LIDAR systems face challenges with semiconductor light sources having short upper-state lifetimes and high peak intensity, which limits their use in pulsed applications, and continuous wave (CW) systems have low photon usage efficiency due to non-single-photon operation.
Innovation Solution
Integration of an optical phased-array transmitter with single-photon detectors using an array of CW sources to effectively pulse illuminate targets by electro-optically steering bright optical intensity patterns, allowing range information to be obtained through measuring pulse delay, enabling broad spectral coverage, high efficiency, and arbitrary scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulsed laser sources are used in conventional LIDAR systems, then range information can be obtained through time-of-flight measurement, but the short upper-state lifetime and high peak intensity of semiconductor light sources limit their application
Solution Approach 1:
The patent applies periodic modulation to continuous wave (CW) laser sources to create effective pulse illumination. By modulating the phase or amplitude of CW lasers at high frequencies and using coherent detection, the system achieves time-of-flight measurement capability without requiring actual pulsed laser emission, thus overcoming the limitation of short upper-state lifetime while maintaining range measurement precision.
2Adaptability or versatility
If continuous wave (CW) laser sources are used, then broad spectral coverage and power scalability are achieved, but photon usage efficiency is low due to non-single-photon operation
Solution Approach 1:
The patent implements coherent detection with local oscillator mixing, which provides feedback-based signal enhancement. The detected signal is mixed with a local oscillator that is phase-locked to the transmitted CW signal, enabling highly efficient photon detection and demodulation. This feedback mechanism allows the system to operate in an effective single-photon detection mode even with CW sources, dramatically improving photon usage efficiency while maintaining broad spectral coverage.
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 the use of CW lasers for LIDAR, offering broader spectral coverage, power scalability, and high-brightness with direct detect modality for 3D imaging, while eliminating the need for additional laser systems and providing eye-safe wavelengths with increased efficiency.
Implementation Method 1
electro-optically steering bright optical intensity patterns
Implementation Method 2
measuring the time-of-flight (i.e., the time it takes for the pulse to travel from the transmitter to the target, be reflected, and travel back to the sensor)
Implementation Method 3
spatiotemporally varying interference pattern
Data Source
AI summary
A method of imaging a scene includes generating a temporally varying optical intensity pattern from at least one continuous wave (CW) light beam. The method also includes illuminating at least one portion of the scene with the temporally varying optical intensity pattern so as to cause a photon to scatter or reflect off the at least one portion of the scene. The photon reflected or scatted from the at least one portion of the scene is detected using a single-photon detector. Based on the temporally varying optical intensity pattern and a time of flight of the photon detected, a distance between the single-photon detector and the at least one portion of the scene is estimated.