Laser Amplifier Energy Management via Intermediary Light Source

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Solution Overview

Problem

Conventional laser light-source apparatuses face challenges in temporarily stopping pulse light output without damaging solid state amplifiers and nonlinear optical elements, leading to degradation of beam propagation characteristics due to thermal lens effects and excessive energy accumulation.

Innovation Solution

A laser light-source apparatus with a control unit that manages the propagation of pulse light through an optical switching element, allowing the second light source to oscillate during output stops and maintaining excitation light power, preventing energy accumulation and thermal issues by controlling the propagation of ASE noise and continuous light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pulse light output is temporarily stopped while maintaining excitation light power, then the population inversion state is prevented from becoming excessive, but the solid state amplifier accumulates excessive energy causing thermal lens effect and beam propagation degradation

Engineering Contradiction:
Improveprevention of giant pulse damageVSAvoidthermal lens effect
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

A second light source acts as an intermediary to consume excess energy in the solid state amplifier during pulse light output stops. This mediator prevents energy accumulation and thermal damage while maintaining system stability, allowing the excitation light to continue pumping without causing harmful population inversion or thermal lensing.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The excess energy that would normally cause harmful thermal accumulation is converted into a beneficial effect by introducing a second light source that consumes this energy productively. The harmful population inversion state is transformed into useful energy consumption by the additional light source, preventing damage while maintaining continuous operation.

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

2Reliability

If the seed light source oscillation is stopped to prevent excessive population inversion, then giant pulse damage is avoided, but the oscillating frequency becomes unstable due to environmental factors

Engineering Contradiction:
Improveprevention of giant pulse damageVSAvoidoscillating frequency stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The second light source serves as a mediator that allows the seed light source to maintain stable oscillation while preventing energy accumulation in the amplifier. By providing an alternative energy consumption path, the system can keep the seed laser running at stable frequency without risking giant pulse formation during output stops.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Duration of action of moving object

If a mode-locked laser is used as seed light source to achieve short pulse width, then high peak power pulse light is obtained, but the oscillating frequency fluctuates due to environmental factors requiring complex synchronization circuits

Engineering Contradiction:
Improvepulse widthVSAvoidsynchronization circuit complexity
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The second light source acts as an energy sink that decouples the seed laser operation from amplifier energy accumulation. This allows the use of mode-locked lasers for short pulse generation without requiring complex synchronization circuits, as the amplifier energy management is handled by the intermediary light source rather than frequency synchronization.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Ease of operation

If a semiconductor laser is used as seed light source for controllable oscillating frequency, then frequency control is achieved, but the pulse energy is extremely small requiring much stronger amplification

Engineering Contradiction:
Improvefrequency controllabilityVSAvoidpulse energy
Core Design Contradiction:
Ease of operationVSPower

Solution Approach 1:

The second light source serves as an energy management intermediary that enables stronger amplification by preventing energy accumulation. This creates a stable amplification environment that can handle the low-input-energy semiconductor laser signals while maintaining frequency controllability, effectively decoupling the seed laser's frequency control capability from amplification stability concerns.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Prevents damage to solid state amplifiers and nonlinear optical elements, ensuring stable beam propagation characteristics and processing quality by managing energy and thermal stability during pulse light output interruptions.

Implementation Method 1

a fiber amplifier configured to amplify the pulse light output from the first light source

Methodology Applied
Scientific EffectOptical amplification: Light

Implementation Method 2

a solid state amplifier configured to amplify the pulse light output from the fiber amplifier

Methodology Applied
Scientific EffectOptical amplification: Light

Implementation Method 3

a nonlinear optical element configured to perform wavelength conversion on the pulse light output from the solid state amplifier

Methodology Applied
Scientific EffectWavelength conversion: Second Harmonic Generation

Implementation Method 4

both require an excitation light source for amplifying light with the same wavelength as laser light amplified by a pumping effect in a laser active region

Methodology Applied
Scientific EffectPumping effect: Light

Data Source

PatentEP3309912B1Laser light-source apparatus and laser pulse light generating method
Publication Date: 2022.11.02 SPECTRONIX CORP
  • EP3309912B1 patent drawingFigure 1
  • EP3309912B1 patent drawingFigure 2A~2C
  • EP3309912B1 patent drawingFigure 3A~3F

AI summary

A laser light-source apparatus includes: a fiber amplifier and a solid-state amplifier configured to amplify pulse light output from a seed light source serving as a first light source; a nonlinear optical element configured to perform wavelength conversion on the pulse light output from the solid-state amplifier; an optical switching element configured to permit or stop propagation of the pulse light from the fiber amplifier to the solid-state amplifier; a second light source that is disposed on an upstream side of the solid-state amplifier and is configured to output laser light that is able to be combined with the pulse light output from the seed light source; and a control unit configured to control the optical switching element in such a manner that the propagation of light is stopped and to perform control in such a manner that the second light source oscillates, at least in an output period of the pulse light from the seed light source.