Dispersive Optical Phased Array for Scalable LiDAR Scanning
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Solution Overview
Problem
Existing dispersive optical phased arrays face challenges in scaling up to a large number of antennas due to excessive waveguide length, increased loss, phase errors, and large chip footprint, making them unsuitable for commercial applications requiring thousands of antennas for LiDAR use.
Innovation Solution
A dispersive optical phased array design comprising M antenna blocks with each block containing nj antennas, where each antenna block acts as a dispersive phased array, using delay lines with optical path length ΔLj,k and phase delay ΔΦj,k = ΔLj,k*2π/λ(t) to ensure all antennas are in phase, and employing phase shifters to equalize phase differences between blocks, allowing for a scalable and symmetrical design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of antennas is increased to achieve the required beam quality and range for LiDAR applications, then the beam quality and detection range are improved, but the waveguide length becomes excessive, leading to increased loss and phase errors
Solution Approach 1:
The optical phased array is divided into multiple antenna blocks, where each block contains a subset of antennas. This segmentation allows the system to achieve the required total number of antennas (for beam quality) while keeping the waveguide connections within each block manageable in length, thereby reducing optical loss and phase errors compared to a monolithic array.
2Measurement precision
If the number of antennas is increased to achieve the required beam quality and range for LiDAR applications, then the beam quality and detection range are improved, but the chip footprint becomes excessively large
Solution Approach 1:
By segmenting the antenna array into multiple blocks that can be arranged in a compact configuration, the system achieves the required number of antennas for beam quality while minimizing the overall chip footprint. The segmented structure allows for more efficient spatial arrangement compared to a linear expansion of a single large array.
3Speed
If a large number of phase shifters are used to control thousands of antennas for fast scanning, then the scanning speed is improved, but the difficulty of accurate control increases
Solution Approach 1:
The phase shifter control system is segmented into multiple independent control groups, one for each antenna block. This reduces the complexity of controlling thousands of phase shifters simultaneously by dividing them into manageable subsets, while still enabling fast scanning through coordinated operation of all blocks.
Solution Approach 2:
Instead of requiring precise control of all phase shifters at all times, the system uses wavelength tuning to achieve the primary scanning function with minimal phase adjustment, reducing the burden on the phase shifter control system while maintaining fast scanning capability.
4Adaptability or versatility
If wavelength tuning is used to scan the beam in one direction while phase shifters control the other direction, then two-dimensional scanning capability is achieved, but the beam quality depends on accurate phase shifter control
Solution Approach 1:
By dividing the antenna array into multiple blocks with independent phase control, the system achieves 2D scanning through the combination of wavelength tuning and block-level phase adjustment. The segmentation allows for more robust beam quality control since phase errors in one block do not propagate to other blocks, maintaining overall beam quality despite the complexity of 2D scanning.
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 design enables a scalable 2D scanning system with a narrow, focused beam and reduced footprint, maintaining beam quality and sampling resolution, even with a large number of antennas, by ensuring all antennas are in phase and using phase shifters to correct phase deviations.
Implementation Method 1
each delay line having an optical path length ΔLj,k, where ΔΦj,k denotes a phase delay of the kth antenna of the jth antenna block, ΔΦj,k being substantially equal to ΔLj,k2π/λ(t)
Implementation Method 2
The antennas 2, which often are formed by a waveguide diffraction grating, radiate light off-chip at a different angle (along the y direction) depending on the wavelength
Data Source
AI summary
A dispersive optical phased array for two-dimensional scanning is disclosed herein. The array comprises antenna blocks positioned adjacent one another. The antenna blocks comprise a plurality of antennas positioned adjacent one another and a plurality of delay lines to couple a coherent source signal to each of the antennas within the block, each delay line having an optical path length. Each of the antenna blocks acts as a dispersive phased array. The antenna blocks are arranged such that the blocks form a larger phased array where the antennas between the blocks are in phase for a discrete set of wavelengths. All antennas over the dispersive phased array can experience the same phase difference such that the beams of the individual antenna blocks align with one of the diffraction orders of the array of blocks.