Graded-Index Fiber Coupling for Hollow-Core Mode Mismatch

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Solution Overview

Problem

The difficulty in forming low-loss connections between hollow-core optical fibers and standard single-mode optical fibers due to mismatched mode field diameters, with existing methods being difficult and expensive to implement.

Innovation Solution

The use of optical couplers with graded-index lenses and ferrules to align and couple hollow-core optical fibers with standard single-mode optical fibers, utilizing graded-index lenses with lengths that match the mode field diameters, and optionally incorporating coreless optical fibers to prevent foreign matter entry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hollow-core optical fiber is used to reduce latency and signal loss, then transmission performance is improved, but connection difficulty increases due to mode field diameter mismatch

Engineering Contradiction:

Improvetransmission performanceVSAvoidconnection difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces a transition component that serves as an intermediary between hollow-core and solid-core optical fibers. This transition component includes a hollow-core section and a solid-core section, enabling mode field diameter matching and facilitating low-loss connections between different fiber types without requiring complex field splicing operations

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs gradual parameter changes in the transition component, where the core diameter and refractive index are progressively adjusted from the hollow-core section to the solid-core section. This gradual transition enables adiabatic mode transformation, allowing the mode field diameter to change smoothly and reducing connection loss between fibers with different mode field diameters

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If fiber tapering is used to match mode field diameters, then connection loss is reduced, but implementation complexity and cost increase

Engineering Contradiction:

Improveconnection lossVSAvoidimplementation complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent incorporates the mode field diameter matching function into the transition component during factory manufacturing. The transition component is pre-configured with the appropriate hollow-core and solid-core sections to provide gradual mode transformation, eliminating the need for complex field tapering operations and simplifying deployment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a simple, inexpensive transition component that can be easily manufactured and deployed. Rather than requiring complex, expensive field splicing equipment and skilled technicians, the solution employs a straightforward connectorizable component that achieves low-loss connections through its built-in mode field diameter matching design

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 low-loss, efficient, and cost-effective connections between hollow-core and standard single-mode optical fibers, allowing for field implementation with consistent performance across varying lens lengths.

Implementation Method 1

a first optical coupler including a first end face operatively coupled to a second end face by a first graded-index lens

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentEP4682599A1Interconnections between optical fibers having hollow-cores and optical fibers having hollow or solid-cores

Publication Date: 2026.01.21 CORNING RES & DEV CORP

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AI summary

A system and method for coupling optical fibers. The system operatively couples a first optical fiber having a hollow-core to a second optical fiber having either a hollow-core or a solid-core using a first optical coupler including a graded-index lens. The first optical coupler has a first end face and a second end face. The first end face is connected to the end face of one of the first and second optical fibers. The second end face defines an optical interface with either the end face of the other of first and second optical fibers, or the end face of a second optical coupler connected to the end face of the other of first and second optical fibers. Each optical fiber and optical coupler is positioned in the bore of either a first or second ferrule, and the ferrules positioned relative to each other to define the optical interface.