Mode Field Expander for LIDAR Fiber Coupling Efficiency
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Solution Overview
Problem
Conventional LIDAR systems using fast-scanning mirrors and single-mode fibers suffer from signal degradation due to angular changes in the scanner mirror, especially at high velocities, leading to reduced coupling efficiency and difficulty in detecting distant targets, particularly with smaller fiber diameters.
Innovation Solution
Employing a mode field expander to increase the mode area of optical beams and target signals, allowing for improved coupling efficiency by converting the mode area of the optical beam and target signal using a mode field converter, which can be implemented in both FM and TOF LIDAR systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional laser source is used with a single-mode optical fiber, then the coupling efficiency is limited, but the system complexity remains low. However, this results in significant power loss and reduced signal quality
Solution Approach 1:
The patent segments the optical fiber system into two distinct parts: a single-mode fiber for precise beam transmission and a multi-mode fiber for flexible coupling. This segmentation allows each fiber type to operate in its optimal mode, reducing overall power loss while maintaining manageable system complexity through modular design
Solution Approach 2:
The patent introduces a mode field expander as an intermediary device between the laser source and the optical fiber. This expander acts as a mediator that transforms the laser beam profile to match the fiber's acceptance characteristics, significantly improving coupling efficiency and reducing power loss without requiring complex alignment systems
2Reliability
If the laser beam diameter is mismatched with the optical fiber core, then coupling efficiency decreases, but adjusting the beam diameter requires additional optical components
Solution Approach 1:
The patent changes the physical parameters of the optical fiber system by using a multi-mode fiber with a larger core diameter that can accommodate various beam sizes. This parameter change eliminates the need for precise beam diameter matching and reduces the number of adjustable optical components required
Solution Approach 2:
The patent implements a dynamic solution where the mode field expander can adjust its expansion ratio to match different laser beam characteristics. This dynamic adaptability allows the system to maintain high coupling efficiency across varying operating conditions without requiring manual realignment or additional switching components
3Measurement precision
If single-mode optical fiber is used for remote sensing, then signal quality is maintained, but the coupling efficiency and power transmission are reduced
Solution Approach 1:
The patent segments the fiber optic system into a multi-mode fiber for power-critical coupling at the transmitter end and a single-mode fiber for precision-critical transmission at the sensing end. This segmentation allows the system to optimize for both high coupling efficiency and high signal quality in different sections
Solution Approach 2:
The mode field expander serves as an intermediary that bridges the gap between the laser source and the fiber system. It transforms the beam to ensure maximum power coupling into the multi-mode fiber, which then maintains signal quality through the single-mode section, thus resolving the trade-off between coupling efficiency and signal quality
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
Enhances signal detection and reduces losses in LIDAR systems by increasing the mode area of optical beams and target signals, thereby improving the performance and manufacturing capabilities of LIDAR systems, especially in detecting minimally reflective targets at a distance.
Implementation Method 1
a mode field expander configured to transform a beam profile of a laser source to a transformed beam profile having a width that corresponds to a mode field width of the optical fiber
Data Source
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AI summary
A light detection and ranging (LIDAR) apparatus is provided that includes an optical source to emit an optical beam towards a target. The LIDAR apparatus further includes a mode field expander operatively coupled to the optical source to expand a mode area of the optical beam.