Dispersion Engineered Phased Array for LiDAR Beam Steering
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Solution Overview
Problem
Current optical phased arrays (OPAs) face limitations in steering range and require a wide wavelength tuning range, making them unsuitable for low-cost, compact applications such as LiDAR systems, due to the need for close antenna spacing and inefficient use of phase shifters.
Innovation Solution
The development of a dispersion engineered optical phased array using slow light waveguides with a near-linear dispersion relation, integrated mode converters, and antennas, allowing for larger angle steering with a smaller wavelength range and reduced laser requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional strip waveguides are used in optical phased arrays, then the device structure is simple and easy to manufacture, but the steering range is limited and requires a wide wavelength tuning range
Solution Approach 1:
The patent applies parameter changes by engineering the dispersion relation of the waveguide. Specifically, it uses photonic crystal waveguides with tailored dispersion characteristics where the group velocity is reduced and the dispersion relation is made near-linear. This changes the fundamental parameter of how wavelength maps to steering angle, enabling a 14° steering range with only a 10 nm wavelength tuning range instead of requiring 100 nm bandwidth, thus resolving the contradiction between manufacturing simplicity and steering range capability
2Manufacturing precision
If antenna spacing is increased to simplify fabrication, then manufacturing precision requirements are reduced, but side lobes increase and energy is lost
Solution Approach 1:
The patent changes the operational parameters of the antenna array by utilizing slow-light waveguides with engineered dispersion. The near-linear dispersion relation and reduced group velocity create a different phase progression along the antenna array, which maintains constructive interference in the main beam direction while suppressing side lobes. This allows the system to achieve good beam quality even with relaxed antenna spacing precision requirements
3Adaptability or versatility
If wavelength tuning range is increased to achieve larger steering angles, then steering range is improved, but laser bandwidth requirements become unachievable for compact integrated lasers
Solution Approach 1:
The patent fundamentally changes the parameter relationship between wavelength and steering angle through dispersion engineering. By creating a waveguide with near-linear dispersion and reduced group velocity, a small change in wavelength (10 nm) produces a large change in the effective refractive index, which in turn produces a large change in steering angle (14°). This inverted parameter relationship resolves the contradiction by achieving large steering range with minimal laser bandwidth requirements
Solution Approach 2:
The patent introduces dynamic control of the optical phase through electro-optic or thermo-optic phase modulators integrated with each antenna element. This dynamic phase control allows precise beam steering within the engineered dispersion regime, enabling the system to achieve its full steering range capability while maintaining compatibility with compact integrated lasers that have limited wavelength tuning ranges
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 dispersion engineered OPA achieves a larger steering range and lower laser bandwidth requirements, enabling compact and cost-effective beam steering for applications like LiDAR and projection systems, with improved performance compared to conventional strip waveguide-based OPAs.
Implementation Method 1
dispersion engineered waveguides with near linear dispersion relation
Implementation Method 2
dispersion engineered slow light waveguide region
Implementation Method 3
a mode converter that couples light from the input waveguide mode to the dispersion engineered waveguide mode
Implementation Method 4
optical antenna regions integrated within the dispersion engineered slow light waveguide region; wherein the optical antenna regions are capable of radiating light out from the dispersion engineered slow light waveguide region
Data Source
AI summary
A photonic crystal optical phased array device has a dispersion engineered slow light waveguide region; a mode coupler region capable of optically coupling an input waveguide to the dispersion engineered slow light waveguide region; and optical antenna regions integrated within the dispersion engineered slow light waveguide region. The dispersion engineered slow light waveguide region has a substantially linear dispersion relation within a predetermined operational bandwidth of the optical phased array device. The optical antenna regions are formed by an alteration of a periodic structure of the photonic crystal and are capable of radiating light out from the dispersion engineered slow light waveguide region.