Laser Emission Feedback Filtering for Stable Pulse Bandwidth

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Solution Overview

Problem

Existing laser systems experience undesired changes in pulse amplitude, bandwidth, and duration due to thermal effects, particularly in applications requiring stable laser emission properties.

Innovation Solution

Incorporating an optical filter outside the cavity, in conjunction with a photodetector, to monitor and stabilize laser emission properties such as pulse bandwidth, duration, and power by filtering out predefined wavelength ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the laser system is operated in constant power mode to maintain stable output, then pulse power is stabilized, but pulse bandwidth and duration change due to temperature variations

Engineering Contradiction:
Improvepulse powerVSAvoidpulse bandwidth
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The patent employs a feedback mechanism where a photodetector monitors the laser emission and provides a feedback signal to the pump source. This closed-loop control system detects changes in pulse properties caused by temperature variations and adjusts the pump power accordingly, allowing the system to maintain stable pulse power while compensating for thermal drift effects on bandwidth and duration.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the operating parameters of the laser system by adjusting the pump source power based on detected pulse properties. By dynamically modifying the pump power parameter in response to temperature-induced changes, the system maintains stable pulse characteristics despite thermal effects on the gain medium and optical components.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If temperature control is not implemented, then the laser system structure remains simple, but pulse properties change due to thermal effects

Engineering Contradiction:
Improvesystem structureVSAvoidpulse duration
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

Instead of implementing complex thermal control systems, the patent uses a feedback mechanism that monitors pulse duration and power with a photodetector and adjusts pump power accordingly. This approach achieves pulse stabilization without requiring complex temperature control hardware, maintaining relative system simplicity while improving pulse property stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces potential mechanical thermal control systems with an optical-electrical feedback system. By using optical detection (photodetector) and electrical control (pump source adjustment), the system achieves pulse stabilization without mechanical thermal management components, reducing overall system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If thermal effects are not compensated, then the system operation is simple, but pulse bandwidth and duration become unstable

Engineering Contradiction:
Improvesystem operationVSAvoidpulse bandwidth stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements automatic feedback control that continuously monitors pulse bandwidth and adjusts pump power to compensate for thermal effects. This automated system maintains pulse bandwidth stability without requiring manual intervention or complex operational procedures, preserving ease of operation while significantly improving reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The laser system performs self-correction by using its own output (monitored by the photodetector) to regulate its pump source. This self-service mechanism automatically compensates for thermal drift and maintains stable pulse properties without external control, keeping the system easy to operate while improving reliability.

Inventive Principle:
Principle #25Self-service

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 optical filter stabilizes laser emission properties, minimizing variations due to temperature changes, ensuring consistent pulse characteristics.

Implementation Method 1

an optical filter located outside the cavity, wherein the optical filter is arranged in optical communication with the photodetector and configured to filter out a predefined range of wavelengths

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 2

a photodetector located outside the cavity, the photodetector configured to monitor the laser emission from the cavity and provide a feedback signal to the pump source

Methodology Applied
Scientific EffectPhotodetection: Photoelectric Effect

Implementation Method 3

a pump source configured to optically pump the gain medium in the cavity

Methodology Applied
Scientific EffectOptical pumping: Absorption (EM radiation)

Implementation Method 4

a cavity comprising a gain medium configured to generate laser emission in the form of laser pulses

Methodology Applied
Scientific EffectStimulated emission: Laser

Data Source

PatentEP4576452A1Laser system for stabilizing laser emission
Publication Date: 2025.06.25 NKT PHOTONICS AS
  • EP4576452A1 patent drawingFigure 1~2
  • EP4576452A1 patent drawingFigure 3~4
  • EP4576452A1 patent drawingFigure 5~6

AI summary

The present disclosure relates to a laser system comprising: a cavity (1) comprising a gain medium (2) configured to generate laser emission in the form of laser pulses, each having a pulse bandwidth and pulse power; a pump source (3) configured to optically pump the gain medium in the cavity; a photodetector (4) located outside the cavity, the photodetector configured to monitor the laser emission from the cavity and provide a feedback signal to the pump source; and an optical filter (5) located outside the cavity, wherein the optical filter is arranged in optical communication with the photodetector and configured to filter out a predefined range of wavelengths in order to stabilize one or more properties of the laser emission, in particular to stabilize the pulse bandwidth, pulse duration and/or pulse power.