Disk Laser ASE Suppression via Segmented Doping

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Solution Overview

Problem

Amplified spontaneous emission (ASE) in disk lasers depletes upper level inversion, leading to reduced laser power and potential failure, especially in high-gain amplifiers, due to parasitic oscillations and thermal load, necessitating operation at lower gain and reduced robustness.

Innovation Solution

A thin disk laser design with a central portion doped at a first concentration for amplification and an annular edge portion doped at a higher concentration for ASE suppression, where the edge portion effectively absorbs ASE photons, preventing re-amplification and reducing thermal damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the laser operates at high gain to increase power output, then the laser power is improved, but ASE depletes the upper level inversion and causes parasitic oscillations that reduce reliability

Engineering Contradiction:

Improvelaser powerVSAvoidlaser reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The laser gain medium is segmented into two distinct regions: a central low-doping region for laser amplification and an annular high-doping region for ASE absorption. This spatial segmentation allows the system to simultaneously achieve high gain operation and effective ASE suppression, resolving the contradiction between power output and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the laser gain medium are assigned different doping concentrations tailored to their specific functions. The central region has low doping concentration optimized for laser amplification, while the annular edge region has high doping concentration optimized for ASE absorption. This local differentiation enables each region to perform its function optimally without compromising the other

Inventive Principle:

Principle #3Local quality

2Power

If the laser operates at high gain to increase power output, then the laser power is improved, but thermal load increases causing potential permanent damage to the laser disk

Engineering Contradiction:

Improvelaser powerVSAvoidthermal damage

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The high-doping annular region converts the harmful ASE radiation into beneficial heat that can be managed, while simultaneously absorbing ASE photons that would otherwise cause parasitic oscillations. The ASE suppression in this region prevents the conversion of laser energy into damaging thermal loads through parasitic lasing, thereby protecting the laser disk from thermal damage while maintaining high power output

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the doping concentration is increased to suppress ASE, then ASE suppression is improved, but the absorption of pump radiation decreases reducing laser gain

Engineering Contradiction:

ImproveASE suppressionVSAvoidlaser gain

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The laser gain medium is divided into two doping concentration zones: a central low-doping region that maintains high pump radiation absorption and laser gain, and an annular high-doping region that provides strong ASE absorption. This segmentation resolves the contradiction by assigning each doping concentration to the region where it is most beneficial

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The doping concentration is locally optimized for each region's function. The central region uses low doping concentration to maximize pump absorption and laser amplification, while the annular edge region uses high doping concentration to maximize ASE absorption. This local optimization allows the system to achieve both high laser gain and effective ASE suppression simultaneously

Inventive Principle:

Principle #3Local 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

The solution effectively suppresses ASE, increasing the laser's operational stability and reliability by preventing parasitic lasing and thermal damage, allowing for higher gain operation without compromising the laser's integrity.

Implementation Method 1

the edge portion effectively absorbs ASE photons, preventing re-amplification and reducing thermal damage

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

a central portion of laser host material doped or fabricated with laser ions at a first predetermined concentration for amplification of laser radiation

Methodology Applied

Scientific EffectLaser amplification: Laser

Implementation Method 3

an annular edge portion doped at a higher concentration for ASE suppression, where the edge portion effectively absorbs ASE photons, preventing re-amplification

Methodology Applied

Scientific EffectAmplified spontaneous emission suppression: Absorption (EM radiation)

Data Source

PatentUS7609741B2Disk laser including an amplified spontaneous emission (ASE) suppression feature

Publication Date: 2009.10.27 THE BOEING CO

AI summary

A laser system may include a first portion of laser host material adapted for amplification of laser radiation and a second portion of laser host material surrounding the first portion which may be adapted for suppression of ASE. The first portion of laser host material and the second portion of laser host material may be respectively doped at a different predetermined concentration of laser ions. A heat exchanger may be provided to dissipate heat from the first portion and the second portion.