Small-Diameter Polarization Maintaining Optical Fiber

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Solution Overview

Problem

The challenge lies in developing a polarization maintaining optical fiber with a smaller overall dimension that maintains excellent geometry and optical properties, while also having high resistance to external interference and improved temperature performance, which is crucial for high-precision optical fiber gyroscopes.

Innovation Solution

A small-diameter polarization maintaining optical fiber is designed with a specific waveguide structure, including a parabolic stress zone and dual buffer layers, and a unique coating technology using ultraviolet curing, which enhances attenuation and crosstalk control, allowing for further miniaturization and high-precision applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the cladding diameter and coating diameter of polarization maintaining optical fiber are reduced, then the volume and overall dimension are decreased, but the resistance to external interference and temperature performance deteriorate

Engineering Contradiction:
Improvevolume of optical fiberVSAvoidresistance to external interference
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by optimizing the diameter ratios between different fiber components. Specifically, it sets the optical fiber core diameter to 5-8 μm, cladding diameter to 80 μm, and coating diameter to 90-140 μm, creating specific ratio relationships that maintain performance while enabling miniaturization. This resolves the contradiction by finding optimal parameter values that balance small size with interference resistance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material structures with multiple layers having different properties. The fiber consists of a core layer, cladding layer, and coating layer, where each layer is optimized for specific functions. The cladding and coating layers provide protective functions while the core maintains optical properties, allowing the fiber to achieve both small size and high reliability through material composition optimization.

Inventive Principle:
Principle #40Composite materials

2Length of moving object

If the diameter of polarization maintaining optical fiber is reduced for miniaturization, then the overall dimension is decreased, but the geometry and optical properties may be compromised

Engineering Contradiction:
Improvediameter of optical fiberVSAvoidgeometry and optical properties
Core Design Contradiction:
Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies local quality by optimizing each layer's properties specifically for its function. The core layer (5-8 μm diameter) is optimized for optical transmission, the cladding layer (80 μm) for stress distribution and geometric stability, and the coating layer (90-140 μm) for protection. This localized optimization of each region's properties maintains overall geometric and optical precision despite the fiber's small overall diameter.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent maintains manufacturing precision by establishing specific parameter ranges and ratio relationships. The core diameter is controlled at 5-8 μm with specific ratio relationships to the cladding diameter (80 μm), ensuring consistent geometric properties. These controlled parameter changes allow miniaturization while preserving the precision required for optical fiber performance.

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 solution provides a polarization maintaining optical fiber with excellent stability characteristics for long-term operation, improved attenuation, and reduced crosstalk, enabling better performance in high-precision optical fiber gyroscope applications and meeting miniaturization requirements.

Implementation Method 1

the material whose coefficient of expansion has a large difference from the cladding material is introduced into the cladding to form the stress zone, the birefringence effect is achieved by compressing the mode field of the light transmitted by the core by stress to maintain the linear polarization properties of the light

Methodology Applied
Scientific EffectStress birefringence: Birefringence

Implementation Method 2

a unique coating technology using ultraviolet curing

Methodology Applied
Scientific EffectUltraviolet curing: Photopolymerisation

Data Source

PatentEP3141937B1Small-diameter polarization maintaining optical fibre
Publication Date: 2020.12.16 FIBERHOME TELECOMMUNICATION TECHNOLOGIES CO LTD
  • EP3141937B1 patent drawingFigure 1~2
  • EP3141937B1 patent drawingFigure 3~4
  • EP3141937B1 patent drawingFigure 5

AI summary

Disclosed is a small-diameter polarization maintaining optical fiber, which relates to the field of special optical fibers. The small-diameter polarization maintaining optical fiber comprises a quartz optical fiber (5); the periphery thereof is provided with an inner coating (6) and an outer coating (8); the interior of the quartz optical fiber (5) is provided with an optical fiber core layer (1) and a quartz cladding (2); two stress zones (4) are arranged between the optical fiber core layer (1) and the quartz cladding (2); a buffer coating (7) is arranged between the inner coating (6) and the outer coating (8); the periphery of each stress zone (4) is provided with a buffer layer (3) which is concentric with the stress zone (4); when a working wavelength of a small-diameter polarization maintaining optical fiber is 1310 nm, the attenuation thereof reaches less than 0.5 dB/km, and the crosstalk reaches -35 dB/km; and when the working wavelength of the small-diameter polarization maintaining optical fiber is 1550 nm, the attenuation thereof reaches less than 0.4 dB/km, and the crosstalk reaches -30 dB/km. The optical fiber not only has excellent stability characteristics of attenuation and crosstalk, but also has the excellent stability characteristic of long-term operation, and can provide a better optical fiber ring for research on a high-precision optical fiber gyroscope, thereby laying the foundation for the development directions of miniaturization and high precision of the optical fiber gyroscope.