Oligomode Fiber Delay Line for Tunable Light Sources

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Solution Overview

Problem

Existing wavelength-tunable light sources face inefficiencies when using monomode fibers for delay lines, leading to mode dispersion and high losses, particularly in the spectral range around 1050 nm, which affects the temporal smearing and attenuation of radiation.

Innovation Solution

Employing oligomode fibers instead of monomode fibers for the delay line, which guides between two and 20 modes, reducing mode dispersion and chromatic dispersion, and compensating for expected losses by having lower attenuation in the oligomode fibers, thereby maintaining high efficiency and precise timing of spectral components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If monomode fibers are used for delay lines, then mode dispersion is reduced, but attenuation increases and efficiency decreases

Engineering Contradiction:
Improvetemporal precisionVSAvoidattenuation
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent changes the modal parameter of the fiber from monomode to oligomode operation. By operating the oligomode fiber in a wavelength range where it guides between 2 and 20 modes, the system achieves lower attenuation while maintaining acceptable temporal precision through careful control of mode dispersion effects.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If oligomode fibers are used for delay lines, then attenuation is reduced and efficiency is improved, but mode dispersion increases causing temporal smearing

Engineering Contradiction:
ImproveattenuationVSAvoidtemporal precision
Core Design Contradiction:
Loss of energyVSMeasurement precision

Solution Approach 1:

The patent carefully selects operational parameters including wavelength range and fiber design to optimize the balance between attenuation and mode dispersion. By operating in specific wavelength ranges and controlling the number of guided modes between 2 and 20, the system minimizes temporal smearing while maintaining low attenuation benefits.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If oligomode fibers are used for delay lines, then chromatic dispersion is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvespectral precisionVSAvoidfiber manufacturing
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent specifies precise manufacturing parameters for the oligomode fibers including core diameter, cladding diameter, and refractive index profiles to achieve the desired mode guidance characteristics. These controlled parameter changes enable reduced chromatic dispersion while maintaining manufacturability through established fiber drawing techniques.

Inventive Principle:
Principle #35Parameter changes

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 use of oligomode fibers in the delay line reduces temporal smearing and attenuation, enabling efficient wavelength tuning with reduced losses and maintaining high efficiency, especially in the 1050 nm spectral range, suitable for Fourier domain mode-locked lasers.

Implementation Method 1

Employing oligomode fibers instead of monomode fibers for the delay line, which guides between two and 20 modes, reducing mode dispersion and chromatic dispersion

Methodology Applied
Scientific EffectMode dispersion reduction: Dispersion (of waves)

Implementation Method 2

Employing oligomode fibers instead of monomode fibers for the delay line, which guides between two and 20 modes, reducing mode dispersion and chromatic dispersion

Methodology Applied
Scientific EffectChromatic dispersion reduction: Dispersion (of waves)

Implementation Method 3

compensating for expected losses by having lower attenuation in the oligomode fibers

Methodology Applied
Scientific EffectAttenuation reduction: Absorption (EM radiation)

Implementation Method 4

The delay paths are set up to bring about a time delay in a light passing through the delay paths over their optical length

Methodology Applied
Scientific EffectTime delay:

Data Source

PatentEP2478599B1Tunable wavelength light source
Publication Date: 2017.09.06 LUDWIG MAXIMILIANS UNIV MUNCHEN
  • EP2478599B1 patent drawingFigure 1~2
  • EP2478599B1 patent drawingFigure 3~4
  • EP2478599B1 patent drawingFigure 5~6B

AI summary

The invention relates to a tunable wavelength light source (100), at least one embodiment thereof comprising at least one fiber-based partial line section (10) and at least one delay line (1). For a wavelength ? of at least one portion of a radiation (S) emitted by the light source (100), the relationship ? (t) = ? (t - t) applies as a function of the time t. t is thereby a particular span of time. The delay line (1) further comprises one or more oligomode fibers (11).