Asymmetric Waveguide Fin Optical Antenna for LiDAR Beam Steering

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Solution Overview

Problem

Current optical phased arrays face challenges in achieving both wide steering angles and long beam projections due to the difficulty in densely packing antenna elements while maintaining precise manufacturing requirements, particularly with the use of diffraction gratings that restrict scale and precision.

Innovation Solution

An optical antenna design featuring a waveguide structure with a waveguide core and fin, where the waveguide fin is placed at a right angle on top of the core, creating an asymmetrical structure that allows for controlled radiation leakage without the need for high-precision lithography, using varying offsets and cross-section dimensions to control leakage rates and beam profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If diffraction gratings are used to couple light from waveguide to free space, then beam steering capability is improved, but manufacturing precision requirements increase and scale is restricted

Engineering Contradiction:

Improvebeam steering capabilityVSAvoidgrating precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent extracts the diffraction grating function from the waveguide structure and implements it through the geometric configuration of the waveguide fin itself. The fin's dimensions and positioning create the necessary phase variations without requiring separate grating structures, thereby eliminating the manufacturing precision challenges associated with traditional gratings while preserving beam steering capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the waveguide structure with the diffraction grating function by using the waveguide fin as both a structural element and a phase-modulating element. This integration eliminates the need for separate grating components and reduces the overall manufacturing complexity while maintaining the beam steering functionality

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If antenna elements are densely packed to achieve wide steering angle, then steering angle range is improved, but beam projection distance decreases

Engineering Contradiction:

Improvesteering angle rangeVSAvoidbeam projection distance

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent applies local quality by varying the waveguide fin dimensions and positioning at different locations along the waveguide core. This creates localized phase variations that control the radiation pattern, enabling wide steering angle while maintaining long beam projection distance through optimized local geometric characteristics

Inventive Principle:

Principle #3Local quality

3Loss of energy

If waveguide fin is placed at offset position, then radiation leakage is improved, but structural symmetry is broken

Engineering Contradiction:

Improveradiation leakageVSAvoidstructural symmetry

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The patent intentionally introduces asymmetry by positioning the waveguide fin at an offset from the waveguide core centerline. This asymmetric configuration creates the necessary modal overlap and radiation leakage while the overall structure maintains sufficient symmetry to ensure stable operation and predictable beam characteristics

Inventive Principle:

Principle #4Asymmetry

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 the generation of optical beams with desired profiles, including collimated and Gaussian beams, suitable for applications like LiDAR and automotive systems, with beam waists up to 30 mm and projection distances of hundreds of meters, while allowing for wide steering angles and dense packing of antenna elements.

Implementation Method 1

This asymmetry creates a non-zero field overlap which couples the guided mode to the radiating mode of the waveguide structure in the vertical direction

Methodology Applied

Scientific EffectMode coupling:

Implementation Method 2

an optical antenna is formed which leaks radiation in the vertical direction, i.e., away from the plane of the substrate and through the top of the waveguide fin

Methodology Applied

Scientific EffectRadiation leakage:

Implementation Method 3

the optical antenna is configured to generate an optical beam with a desired beam profile

Methodology Applied

Scientific EffectBeam formation:

Implementation Method 4

the optical antenna is configured to generate an optical beam with a collimated and substantially Gaussian beam profile

Methodology Applied

Scientific EffectCollimation:

Data Source

PatentUS20240345387A1An optical antenna for optical phased antenna arrays

Publication Date: 2024.10.17 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

An optical antenna includes a waveguide structure having a waveguide core and a waveguide fin intersecting substantially under a right angle. A height of the waveguide fin is larger than a height of the waveguide core; and the width of the waveguide core is equal to or larger than twice a height of the waveguide core; and the height of the waveguide fin is equal to or larger than twice a width of the waveguide fin. The waveguide fin is off centered with respect to the waveguide core at an offset, thereby forming an optical antenna configured to leak radiation in a radiation direction. Embodiments relate to an optical phased antenna array comprising a plurality of such optical antennas arranged in an array configuration.