Hollow-Core Waveguide End Geometry for Low-Loss Optical Decoupling

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Solution Overview

Problem

Existing decoupling devices for hollow-core optical waveguides suffer from significant insertion loss when extracting light signals, limiting the performance of optical systems.

Innovation Solution

The cross-sectional area of the core in the end section is designed to differ in size and/or shape from the main section, with a gradual increase in size towards the end face, and a lens with varying refractive indices is used to project the light beam onto the exit surface, reducing insertion loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conventional decoupling device is used to extract light signals from hollow-core optical waveguides, then the light can be extracted, but significant insertion loss occurs

Engineering Contradiction:
Improveinsertion lossVSAvoidsystem performance
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The core cross-sectional area is varied locally in the end section of the hollow-core optical waveguide, creating a gradual transition from the larger core area in the main section to a smaller core area at the end face. This local structural modification optimizes the optical field distribution and reduces insertion loss at the coupling interface without affecting the overall waveguide structure

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the core cross-sectional area along the length of the waveguide. By gradually reducing the core area from the main section to the end face, the optical mode is transformed to better match the coupling interface, thereby minimizing insertion loss and improving system performance

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the core cross-sectional area is varied in the end section to reduce insertion loss, then coupling efficiency improves, but the device structure becomes more complex

Engineering Contradiction:
Improveinsertion lossVSAvoidwaveguide structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The hollow-core optical waveguide is divided into two distinct sections: a main section with a constant larger core cross-sectional area and an end section with a gradually varying smaller core cross-sectional area. This segmentation allows the waveguide to maintain simple structure in the main transmission region while introducing complexity only where needed for optimal coupling at the end face

Inventive Principle:
Principle #1Segmentation

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 design significantly reduces insertion loss, enhancing light guidance and enabling high-bandwidth, low-loss communication networks.

Implementation Method 1

a lens (4) with an entrance surface (4a) facing the first end section (9) and an exit surface (4b) facing away from the second end section (9), and a holder (3) holding the first end section (9) and the lens (4), wherein the lens (4) is designed and arranged such that a beam of light emerging from the first end section (9) strikes the entrance surface (4a) and is projected as a convergence beam of light onto the exit surface (4b)

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4664167A1Decoupling device and optical waveguide plug having the same
Publication Date: 2025.12.17 CUBE OPTICS AG
  • EP4664167A1 patent drawingFigure 1~2
  • EP4664167A1 patent drawingFigure 3
  • EP4664167A1 patent drawingFigure 4

AI summary

Decoupling device for decoupling an optical signal from a hollow-core optical waveguide, wherein the decoupling device comprises: a hollow-core optical waveguide with a first end section, a second end section, each comprising an end face of the optical waveguide, and a main section arranged between the first end section and the second end section, wherein the hollow-core optical waveguide has a core designed to receive light signals and a cladding surrounding the core, and wherein the hollow-core optical waveguide has a length I, the core having a constant, non-circular cross-sectional area within the main section.