Laser-Stripped Optical Fiber Recoating to Prevent Interface Cracking

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Solution Overview

Problem

In the manufacturing of long optical fibers for submarine cables, the interface between the protective resin and the original coating resin often experiences peeling and cracking due to side pressure during bobbin winding, especially when a two-layer coating structure with a soft primary layer is used, leading to quality inconsistencies and potential damage to the glass fiber.

Innovation Solution

A method involving laser stripping of the coating layer with a pulse width of 50 fs to 500 ps, wavelength of 340 nm to 1100 nm, and pulse energy density of 10 J/cm², forming a tapered shape to reduce stress concentration and prevent cracking, while avoiding damage to the glass fiber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a two-layer coating structure with a soft primary layer is used, then the optical fiber can withstand side pressure during bobbin winding, but peeling and cracking occur at the interface between the protective resin and the original coating resin

Engineering Contradiction:

Improveside pressure resistanceVSAvoidinterface adhesion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent replaces mechanical stripping methods with laser irradiation to remove the coating layer. The laser light with pulse width of 50 fs to 500 ps selectively ablates the coating material without mechanically contacting the fiber, eliminating stress concentration that causes interface peeling and cracking while maintaining the protective function of the coating structure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and properties of the coating layer through controlled laser irradiation parameters (pulse width 50 fs to 500 ps, specific energy density). This transforms the coating removal process from a mechanical action to a controlled thermal/ablation process, preventing interface damage while achieving complete coating removal

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional stripping methods are used, then the coating layer is removed, but peeling and cracking occur at the interface between protective resin and coating resin

Engineering Contradiction:

Improvecoating removalVSAvoidinterface integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces mechanical stripping tools and processes with laser irradiation. The laser beam selectively removes the coating layer through ablation without physical contact, eliminating the mechanical stresses that cause interface peeling and cracking while maintaining ease of manufacture through a streamlined, contactless process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces laser light as an intermediary between the stripping process and the coating layer. The laser energy acts as a mediator that transfers energy to the coating material for removal without requiring mechanical contact, thereby protecting the interface between the protective resin and coating resin from damage

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If the coating layer is completely stripped, then fusion splicing can be performed, but the glass fiber becomes vulnerable to damage

Engineering Contradiction:

Improvesplicing preparationVSAvoidglass fiber damage risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by selectively removing the coating layer only from the specific region required for splicing while preserving the coating on the rest of the fiber. This localized stripping approach prepares the fiber for fusion splicing while maintaining protective coating elsewhere, reducing the glass fiber's vulnerability to damage

Inventive Principle:

Principle #3Local quality

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 approach prevents cracks in the protective resin, ensures stable optical fiber quality, and reduces the risk of damaging the glass fiber, achieving consistent adhesion and improved fusion-splicing intensity.

Implementation Method 1

the stripping step is a step of irradiating the coating layer with a laser light to strip the coating layer

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS12085754B2Method for producing optical fiber with laser stripping step, and optical fiber thereof

Publication Date: 2024.09.10 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A method for manufacturing an optical fiber, the method including: a stripping step of partially stripping a coating layer 12, 13 of the optical fiber 10; a splicing step of fusion-splicing an exposed end surface of a glass fiber 11; and a recoating step of recoating a protective resin 15 covering a stripped portion of the coating layer 12, 13 and an exposed portion of the glass fiber 11, in which the stripping step irradiates the coating layer 12, 13 with a laser light to strip the coating layer 12, 13. A pulse width of the laser light is 50 fs or more and 500 ps or less.