Fiber Laser Pump Element Sequencing for Waste Heat and Light Control

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Solution Overview

Problem

High-power fiber laser systems face issues with excessive heat and light transmission to downstream components due to unabsorbed pump light, leading to thermal instabilities and potential damage, particularly when using unlocked pump diodes that shift wavelengths away from peak absorption.

Innovation Solution

Control individual pump elements asynchronously to minimize unabsorbed pump light transmission by progressively increasing the drive current levels, ensuring each element reaches full power before activating the next, thereby optimizing current levels to align with peak absorption wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If pump elements are operated at lower drive current levels, then the system can operate at lower power levels, but unabsorbed pump light increases causing excessive heat and damage to downstream components

Engineering Contradiction:

Improvelaser output powerVSAvoidunabsorbed pump light transmission

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts the drive current levels of individual pump elements based on the requested laser power level. Instead of operating all pump elements at fixed current levels, the controller continuously optimizes the current distribution to maximize absorption efficiency at each power level, thereby minimizing unabsorbed pump light transmission to downstream components.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters (drive current levels) of pump elements to align with peak absorption wavelengths of the gain medium. By adjusting the current levels individually for each pump element, the system optimizes the spectral output to match the absorption characteristics of the doped fiber, reducing unabsorbed pump light and improving overall efficiency.

Inventive Principle:

Principle #35Parameter changes

2Speed

If multiple pump elements are operated simultaneously at low current levels, then the system can respond quickly to power requests, but wavelength drift from unlocked pump diodes increases causing misalignment with peak absorption

Engineering Contradiction:

Improvepower level response speedVSAvoidwavelength alignment with peak absorption

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system segments the pump elements and controls them individually rather than as a single group. This allows selective activation and independent current level adjustment of specific pump elements, enabling precise control over the combined spectral output to maintain alignment with peak absorption wavelengths while responding quickly to power requests.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller uses feedback mechanisms to monitor and adjust the drive current levels of individual pump elements based on the requested laser power level and known absorption characteristics of the gain medium. This feedback loop ensures that pump elements are operated at current levels that produce wavelengths aligned with peak absorption, compensating for drift in unlocked pump diodes.

Inventive Principle:

Principle #23Feedback

3Loss of energy

If pump elements are activated in sequence rather than simultaneously, then unabsorbed pump light is reduced, but the system response time to power requests increases

Engineering Contradiction:

Improveunabsorbed pump lightVSAvoidpower level response time

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The controller pre-calculates and stores optimal drive current level assignments for different requested laser power levels. When a power request is received, the system can quickly retrieve and implement the appropriate current level configuration without requiring sequential activation of pump elements, thus reducing response time while maintaining low unabsorbed pump light levels through optimized current distribution.

Inventive Principle:

Principle #10Preliminary action

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

Reduces peak transmittance of pump power to downstream components, minimizing heat generation and improving optical-to-optical efficiency while protecting components from damage.

Implementation Method 1

a laser source comprising a plurality of pump elements configured to generate laser light

Methodology Applied

Scientific EffectLaser emission: Laser

Implementation Method 2

the strong absorption also allows for shorter fibers to be used in any given architecture which can be beneficial to push to higher peak powers before the detrimental onset of non-linear effects

Methodology Applied

Scientific EffectAbsorption: Absorption (EM radiation)

Implementation Method 3

the desired optical power is guided in the fiber core, but some power may also be present in the fiber cladding

Methodology Applied

Scientific EffectStimulated emission: Laser

Data Source

PatentUS12451668B2Methods, systems and apparatus for reducing waste heat and/or light in fiber lasers

Publication Date: 2025.10.21 NLIGHT INC

AI summary

In an example, the disclosed technology includes a laser source, comprising a plurality of pump elements configured to generate laser light, a controller coupled to the plurality of pump elements, configured to select individual drive current levels to be provided to respective ones of the plurality of pump elements responsive to a request for a laser power level and at least one power supply coupled to one or more of the plurality of pump elements for driving individual pump elements at selected drive currents.