All-Fiber Chirped Pulse Broadening With Subpicosecond Compression

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Solution Overview

Problem

Existing systems fail to effectively spectral broaden and shorten chirped laser pulses to subpicosecond duration while maintaining an all-fiber configuration, as they are prone to environmental disturbances and require free-space optics.

Innovation Solution

A system comprising a fiber-based source, spectral filter, and amplifier, utilizing self-phase modulation (SPM) to shorten and broaden chirped laser pulses via an all-fiber configuration, using polarization maintaining (PM) fibers and rare-earth-doped optical fibers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If free-space optics are used to compress chirped pulses to subpicosecond duration, then pulse duration is reduced below 1.5 ps, but the system becomes sensitive to environmental disturbances and requires alignment

Engineering Contradiction:

Improvepulse durationVSAvoidenvironmental sensitivity

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent replaces free-space optical compression systems with a fiber-based compression system. The fiber optic compressor uses nonlinear optical effects within the fiber to compress pulses, eliminating the need for free-space optics, mirrors, and gratings that are sensitive to environmental disturbances. This substitution maintains pulse compression capability while achieving environmental insensitivity and alignment-free operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operational parameters by using normal dispersion regime in the fiber instead of anomalous dispersion. This parameter change enables pulse compression through soliton dynamics and nonlinear effects within the fiber, achieving subpicosecond pulse duration while maintaining all-fiber configuration that is inherently protected from environmental factors.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If anomalous dispersion regime is used for supercontinuum generation, then broadband light is generated, but coherence is spoiled by soliton effects and modulation instability

Engineering Contradiction:

Improvespectral broadening capabilityVSAvoidpulse coherence

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent inverts the conventional approach by using normal dispersion regime instead of anomalous dispersion for supercontinuum generation. In the normal dispersion regime, self-phase modulation followed by optical wave breaking produces spectral broadening while maintaining high coherence and pulse-to-pulse stability, avoiding the coherence-spoiling effects of soliton fission and modulation instability that occur in anomalous dispersion.

Inventive Principle:

Principle #13The other way round (Inversion)

3Use of energy by moving object

If ultrafast fiber lasers operating in dissipative soliton regime are used, then high energy pulses are delivered, but pulse duration exceeds 1.5 ps and cannot be compressed with microstructured fibers

Engineering Contradiction:

Improvepulse energyVSAvoidpulse duration

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of moving object

Solution Approach 1:

The patent applies preliminary spectral filtering to the chirped pulses before compression. By filtering the spectrum of the dissipative soliton pulses and then compressing them in a fiber with appropriate dispersion characteristics, the system achieves subpicosecond pulse duration while retaining the high energy content. This preliminary action prepares the pulses for effective compression without requiring free-space optics.

Inventive Principle:

Principle #10Preliminary 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

Achieves spectral broadening and shortening of chirped laser pulses to below 1.5 ps duration without environmental sensitivity, maintaining pulse coherence and stability.

Implementation Method 1

for amplifying them and spectrally broadening them in an optical fiber inside the fiber-based amplifier via nonlinear effects

Methodology Applied

Scientific EffectSelf-phase modulation (SPM):

Data Source

PatentEP4610721A1System and method for spectral broadening of chirped laser pulses

Publication Date: 2025.09.03 FLUENCE SP ZOO

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AI summary

The subject matter of the invention is a system for spectral broadening of chirped laser pulses characterized in that the system comprises a fiber-based source (1), a fiber-based spectral filter (2) and a fiber-based amplifier (3), wherein said fiber-based components (1, 2, 3) of the system are optically connected by optical fibers (4). The invention also relates to a method for spectral broadening of chirped laser pulses characterized in that it is conducted in the system according to the invention, wherein the chirped laser pulses are created in a fiber-based source (1), then the chirped laser pulses are shortened down to a duration below 1,5 ps in the fiber-based spectral filter (2) and next the filtered chirped laser pulses are amplified and spectrally broadened in the fiber-based amplifier (3) via nonlinear effects.