Optical Fiber Array With Tapered Ferrule Hole

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Solution Overview

Problem

Existing optical fiber arrays face challenges in maintaining positional accuracy when the cladding diameters of optical fibers are reduced, leading to deteriorated alignment and increased coupling losses.

Innovation Solution

An optical fiber array with a beam expanding portion at the distal end surface and a ferrule having a tapered optical fiber holding hole, where the inner diameter decreases towards the end surface, allowing the distal end surfaces of single-core fibers to abut and maintain precise positioning, even with reduced cladding diameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the cladding diameter of optical fibers is reduced, then the mode field diameter can be expanded, but the positional accuracy and alignment of the optical fibers deteriorate

Engineering Contradiction:

Improvemode field diameterVSAvoidpositional accuracy

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The optical fibers with reduced cladding diameters are nested within a ferrule structure that provides mechanical support and positional stability. The ferrule acts as an outer container that compensates for the reduced structural integrity of the thinner-clad fibers, allowing them to maintain precise alignment despite their smaller size.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention changes the geometric parameters of the ferrule, specifically implementing a tapered inner diameter that decreases toward the end surface. This parameter change creates a mechanical constraint that compensates for the reduced cladding diameter, ensuring that the optical fibers maintain their positional accuracy even with minimized cladding sizes.

Inventive Principle:

Principle #35Parameter changes

2Shape

If the cladding diameter is minimized, then the beam expanding capability is improved, but the coupling losses increase due to deteriorated alignment

Engineering Contradiction:

Improvebeam expanding capabilityVSAvoidcoupling losses

Core Design Contradiction:

ShapeVSLoss of energy

Solution Approach 1:

The optical fibers are nested within the ferrule's tapered cavity, which provides mechanical stabilization. This nesting structure ensures that even though the fibers have minimal cladding for beam expansion, they remain precisely positioned to minimize coupling losses during connection.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The ferrule exhibits local quality variation through its tapered inner diameter, which is narrower at the end surface where the optical fibers are located. This localized geometric feature provides enhanced mechanical constraint precisely where needed, maintaining alignment accuracy without affecting the overall beam expanding capability of the minimized-clad fibers.

Inventive Principle:

Principle #3Local quality

3Volume of moving object

If the cladding diameter is reduced, then the optical fiber size is minimized, but the positional stability and alignment precision deteriorate

Engineering Contradiction:

Improveoptical fiber sizeVSAvoidpositional stability

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The minimized-clad optical fibers are nested within the ferrule structure, which provides the mechanical stability and positional support that the small-sized fibers would otherwise lack. The ferrule acts as a protective and positioning housing that enables the optical fibers to maintain their reduced size while achieving the necessary positional stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The ferrule's inner diameter parameter is changed to a tapered profile that decreases toward the end surface. This parameter modification creates a mechanical constraint that stabilizes the position of the optical fibers, compensating for the reduced cladding diameter and ensuring consistent alignment precision.

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

This configuration enhances the positional accuracy and stability of the optical fibers, reducing coupling losses and maintaining precise alignment, even when cladding diameters are minimized.

Implementation Method 1

The coating-removed portion is heated by the microburner. Due to this heating, an additive in the optical fiber in the coating-removed portion thermally diffuses, and the mode field diameter of the optical fiber is expanded.

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Implementation Method 2

The optical fiber holding hole has a tapered portion whose inner diameter decreases toward the end surface and against which the distal end surfaces abut.

Methodology Applied

Scientific EffectMechanical constraint:

Data Source

PatentUS11714242B2Optical fiber array and optical fiber connection structure

Publication Date: 2023.08.01 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

An optical fiber array includes a plurality of single-core fibers each having a core and a cladding and each having, in a distal end surface thereof, a beam expanding portion capable of expanding a mode field diameter (MFD) of light propagating in the core, and a ferrule having an optical fiber holding hole into which the plurality of single-core fibers are inserted, and an end surface in which the optical fiber holding hole opens. A cladding diameter of each of single-core fiber in the beam expanding portion decreases toward the distal end surface. The optical fiber holding hole has a tapered portion whose inner diameter decreases toward the end surface and against which the distal end surfaces abut.