Master Oscillator Power Amplifier Laser Pulse Stabilization

Solution Overview

Problem

MO-PA type fiber pulse laser apparatuses face a disadvantage where the first pulse output is significantly smaller due to the slow start-up time of the power amplifier unit, leading to unstable population inversion and difficulty in maintaining constant pulse peak values across subsequent pulses.

Innovation Solution

The method involves starting the master oscillator unit before the power amplifier unit and transitioning it to continuous oscillation upon power amplifier activation, synchronizing the excitation light source output with a trigger signal, and adjusting it back to pulse operation to equalize the first pulse with subsequent pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the power amplifier unit is started immediately with pulse operation, then the response time is reduced, but the first pulse output becomes significantly smaller due to slow population inversion buildup

Engineering Contradiction:

Improvestart-up timeVSAvoidpulse output stability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The master oscillator unit is started in advance before the power amplifier unit to pre-build population inversion in the amplification medium. This preliminary action ensures that when the power amplifier is activated, the population inversion is already sufficient to produce stable first pulse output, eliminating the need to wait for slow inversion buildup.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The master oscillator unit operates continuously in a low-power state before and during the power amplifier start-up, maintaining continuous population inversion buildup in the amplification medium. This continuous useful action ensures that the inversion level is always ready, eliminating gaps in the inversion buildup process that would otherwise cause unstable first pulses.

Inventive Principle:

Principle #20Continuity of useful action

2Reliability

If the master oscillator unit is started earlier to pre-build population inversion, then the first pulse output is stabilized, but the overall cycle time increases

Engineering Contradiction:

Improvefirst pulse output stabilityVSAvoidpulse operation cycle time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The master oscillator unit is started in advance before the power amplifier unit to pre-build population inversion in the amplification medium. This preliminary action ensures that when the power amplifier is activated, the population inversion is already sufficient to produce stable first pulse output, eliminating the need to wait for slow inversion buildup.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses periodic switching between master oscillator-only operation and combined master oscillator-power amplifier operation, optimizing the balance between pre-building population inversion and maintaining high productivity during the periodic cycles.

Inventive Principle:

Principle #19Periodic action

3Speed

If the power amplifier unit uses high excitation power to quickly build population inversion, then the start-up time is reduced, but energy consumption and heat generation increase

Engineering Contradiction:

Improvepopulation inversion buildup speedVSAvoidexcitation energy consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The master oscillator unit is started in advance before the power amplifier unit to pre-build population inversion in the amplification medium. This preliminary action ensures that when the power amplifier is activated, the population inversion is already sufficient to produce stable first pulse output, eliminating the need to wait for slow inversion buildup.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies partial excitation power during the pre-build phase using only the master oscillator, then applies full excitation power only when needed during the power amplifier operation phase, avoiding excessive energy consumption while still achieving fast inversion buildup when required.

Inventive Principle:

Principle #16Partial or excessive 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

This approach accelerates population inversion in the amplification medium, stabilizes pulse output, and allows for consistent pulse magnitude across all pulses without increasing apparatus complexity or costs, reducing the time to achieve stable output.

Implementation Method 1

a laser output depends generally on an output of an excitation light source, such as a laser diode (LD) of a power amplifier (PA) unit

Methodology Applied

Scientific EffectStimulated emission: Laser

Implementation Method 2

starting the master oscillator unit before starting the power amplifier unit... accelerates population inversion in the amplification medium

Methodology Applied

Scientific EffectOptical pumping: Absorption (EM radiation)

Data Source

PatentUS7656913B2Fiber pulse laser apparatus and method of controlling the same

Publication Date: 2010.02.02 FUJIKURA LTD

AI summary

A method of controlling a pulse output in a master oscillator-power amplifier type fiber pulse laser apparatus including a master oscillator unit and a power amplifier unit connected to the master oscillator unit is provided. The method includes starting the master oscillator unit before starting the power amplifier unit.