Pump Radiation Arrangement Wavelength Stabilization

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Solution Overview

Problem

High-power pump radiation arrangements for laser-active media face efficiency reduction due to wavelength destabilization and thermal effects, leading to decreased beam quality and reduced absorption efficiency at high power levels.

Innovation Solution

A pump radiation arrangement incorporating a wavelength-selective element, such as a grating structure or interference filter, to stabilize the pump radiation wavelength and a retro-reflector to increase absorption efficiency, while filtering out undesirable spectral portions that could destabilize the pump source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the pump radiation path through the laser-active medium is extended to increase absorption efficiency, then pump efficiency is improved, but thermal effects worsen leading to degraded beam quality

Engineering Contradiction:

Improvepump efficiencyVSAvoidbeam quality

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The pump radiation path is segmented into multiple passes through the laser-active medium rather than a single long path. The retro-reflector causes the pump radiation to traverse the medium multiple times in sequence, achieving high absorption efficiency while maintaining short individual pass lengths to minimize thermal effects and preserve beam quality.

Inventive Principle:

Principle #1Segmentation

2Productivity

If a retro-reflector is used to double the pump radiation path through the laser medium, then absorption efficiency is maximized, but undesirable spectral portions are reflected back to the pump source causing wavelength destabilization

Engineering Contradiction:

Improveabsorption efficiencyVSAvoidpump radiation wavelength

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The wavelength-selective element extracts and removes the undesirable spectral portions from the pump radiation before the retro-reflector reflects the radiation back to the pump source. By filtering out these problematic wavelengths, the pump source wavelength stability is maintained while the retro-reflector continues to provide the beneficial path doubling for absorption enhancement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Different spectral components of the pump radiation are treated differently: desirable wavelengths are reflected back by the retro-reflector to increase absorption, while undesirable spectral portions are selectively filtered out by the wavelength-selective element. This local quality differentiation resolves the contradiction between absorption efficiency and wavelength stability.

Inventive Principle:

Principle #3Local quality

3Power

If the pump radiation spectrum is expanded to cover broader wavelength ranges, then more pump power can be delivered, but absorption efficiency decreases due to mismatch with the narrow absorption line of the laser-active medium

Engineering Contradiction:

Improvepump powerVSAvoidabsorption efficiency

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The retro-reflector provides optical feedback by reflecting the pump radiation back through the laser-active medium. This feedback mechanism allows the pump radiation to interact with the medium multiple times, increasing the effective absorption probability without requiring spectral expansion, thereby maintaining high absorption efficiency while delivering substantial pump power.

Inventive Principle:

Principle #23Feedback

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 solution enhances pump efficiency and maintains beam quality by stabilizing the pump radiation wavelength and increasing absorption, even at high power levels, thereby improving the output power of the laser or amplifier.

Implementation Method 1

a wavelength-selective element for preventing a wavelength destabilization of the pump radiation source by filtering out undesirable spectral portions of pump radiation that are not absorbed by the laser-active medium

Methodology Applied

Scientific EffectWavelength-selective filtering: Filter (optical)

Implementation Method 2

a retro-reflector for reflecting pump radiation that is not absorbed by the laser-active medium along substantially the same beam path or beam travel back to the pump radiation source

Methodology Applied

Scientific EffectRetro-reflection: Retroreflector

Implementation Method 3

a laser-active medium through which the pump radiation passes in a bidirectional manner

Methodology Applied

Scientific EffectOptical absorption: Absorption (EM radiation)

Data Source

PatentUS9331451B2Pump radiation arrangement and method for pumping a laser-active medium

Publication Date: 2016.05.03 TRUMPF LASER GMBH CO KG

AI summary

The disclosure relates to a pump radiation arrangement comprising: a pump radiation source for producing pump radiation, a means for stabilizing the wavelength of the pump radiation source and a laser-active medium through which the pump radiation passes in a bidirectional manner. The pump radiation arrangement also has a retro-reflector for reflecting pump radiation which is not absorbed by the laser-active medium back to the pump radiation source and a wavelength-selective element for preventing a wavelength destabilization of the pump radiation source by filtering out undesirable spectral portions of pump radiation which is not absorbed by the laser-active medium. The invention also relates to an associated method for pumping a laser-active medium.