Multi-Junction Laser Diodes for Higher-Power LiDAR Range
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Solution Overview
Problem
Current LiDAR systems face limitations in peak power and cost due to the use of single junction laser diodes, which restrict range capability and increase system cost, while multi-junction solutions face challenges in brightness and reliability.
Innovation Solution
Implementing a LiDAR system with multi-junction laser diodes and semiconductor optical amplifiers, combined with coherent receivers and injection locking techniques, to enhance peak power and sensitivity, thereby increasing range capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple laser diodes are mounted adjacent to each other to achieve higher power levels, then output power increases, but brightness of the laser source decreases due to distance between emitters
Solution Approach 1:
The patent merges multiple laser diodes into a single integrated package with a common emitter structure, allowing the emitters to be positioned closer together while maintaining high power output. This combining approach resolves the contradiction by achieving both high power and high brightness simultaneously.
Solution Approach 2:
The patent transitions from a planar arrangement of multiple laser diodes to a three-dimensional stacked configuration, where emitters are positioned in different vertical layers. This dimensional change allows the emitters to be closer together in the critical horizontal direction while maintaining the power output, thereby improving brightness without sacrificing power.
2Power
If fiber laser is used to provide very high peak power levels, then peak power increases, but system cost increases due to multiple laser diodes, gratings, endcaps, and mode strippers
Solution Approach 1:
The patent extracts and eliminates the complex resonator components (gratings, endcaps, mode strippers) from the laser system, achieving high peak power through a simplified direct-diode pumping approach. This extraction of unnecessary components dramatically reduces manufacturing complexity and cost while maintaining high power performance.
Solution Approach 2:
The patent employs a simpler, more cost-effective laser diode structure that can be manufactured at lower cost compared to fiber laser systems. The design accepts that individual laser diodes have finite lifespans but achieves high peak power through multiple diodes working in parallel, providing an economical solution for the application.
3Ease of manufacture
If single junction laser diodes are used, then system cost decreases, but output power and beam quality are limited to less than 30 Watts
Solution Approach 1:
The patent combines multiple single-junction laser diodes into a single integrated package, merging their individual power outputs to achieve high total power levels (100 Watts or more) while maintaining the cost advantages of single-junction technology. The common emitter structure enables efficient combining of multiple diodes.
Solution Approach 2:
The patent employs dynamic control of the laser diodes through injection locking, where a master laser synchronizes multiple slave diodes. This dynamic synchronization allows the system to maintain high power output while improving beam quality through coherent operation, overcoming the static limitations of individual diodes.
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 proposed solution significantly enhances LiDAR range capability and sensitivity, overcoming atmospheric challenges and reducing system costs by leveraging multi-junction laser diodes and amplifiers.
Implementation Method 1
multi-junction laser diodes for higher peak power
Implementation Method 2
multi-junction semiconductor optical amplifiers
Implementation Method 3
operating the pulsed system with an injection locked multi-junction transmitter and a coherent receiver greatly increases the sensitivity of the receiver
Data Source
AI summary
A time-of-flight LiDAR system that uses multi-junction laser diodes, for higher peak power than a single junction laser diode can provide, will provide in greater range capability for the LiDAR system. An additional approach to extending range is to continue to increase the output power of the transmitter using multi-junction semiconductor optical amplifiers. In addition to increasing the output power of the laser transmitter, it is also possible to increase the sensitivity of the receiver by using a single junction semiconductor optical amplifier. Finally, operating the pulsed system with an injection locked multi-junction transmitter and a coherent receiver greatly increases the sensitivity of the receiver.