Graded-index first cladding reduces feed light transmission loss

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Solution Overview

Problem

There is a need for improved optical power supply efficiency, particularly in reducing transmission loss in the first cladding of optical fibers to enhance the transmission efficiency of feed light in power over fiber systems.

Innovation Solution

The use of semiconductor materials with short wavelengths for semiconductor lasers and photoelectric conversion elements, along with a graded-index first cladding in optical fibers, to optimize light-electricity conversion efficiency and reduce transmission loss in the optical power supply system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a core transmits signal light and a first cladding transmits feed light, then optical power supply function is achieved, but transmission loss in the first cladding increases

Engineering Contradiction:
Improvetransmission loss in first claddingVSAvoidoptical power supply efficiency
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The first cladding is designed with a graded-index structure where the refractive index varies radially, creating different optical properties at different locations within the cladding. This local variation in refractive index optimizes light confinement and reduces transmission loss specifically in the feed light transmission region without affecting the signal light transmission in the core.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the refractive index parameter of the first cladding by introducing a graded-index profile instead of a uniform index. This parameter change optimizes the optical path for feed light transmission, reducing transmission loss and improving overall optical power supply efficiency while maintaining the dual-function capability of the optical fiber.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If conventional optical fiber structure is used, then manufacturing simplicity is maintained, but feed light transmission efficiency is insufficient

Engineering Contradiction:
Improvefeed light transmission efficiencyVSAvoidoptical fiber structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The optical fiber structure applies local quality by creating a graded-index region specifically in the first cladding while keeping the core structure simple. This localized complexity only where needed (in the feed light transmission region) improves transmission efficiency without significantly complicating the overall fiber manufacturing process.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The first cladding uses a composite refractive index structure combining regions of different indices (higher index near the core, lower index toward the outer cladding). This composite approach optimizes light transmission properties while maintaining compatibility with conventional fiber manufacturing techniques.

Inventive Principle:
Principle #40Composite materials

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 enhances the photoelectric conversion efficiency and reduces transmission loss, thereby improving the overall optical power supply efficiency in power over fiber systems.

Implementation Method 1

a first cladding that is formed around the core, has a refractive index lower than that of the core, and transmits the feed light

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

graded-index first cladding in optical fibers

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 3

an optical receiver that operates with electric power obtained by converting the feed light transmitted through the first cladding of the optical fiber

Methodology Applied
Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentEP3930146B1Optical fiber power supply system and optical fiber cable
Publication Date: 2023.02.15 KYOCERA CORP
  • EP3930146B1 patent drawingFigure 1
  • EP3930146B1 patent drawingFigure 2
  • EP3930146B1 patent drawingFigure 3

AI summary

An optical fiber cable (200) in an optical fiber power supply system (1) has: a core (210) for transmitting signal light (125, 325); a first clad (220) that is located in contact around the core and that is for transmitting power supply light (112); and a second clad (221) that is located in contact around the first clad. A distribution of a refractive index in the radial direction of the first clad exhibits a gradual decrease from an inner position (r2) which marks a local maximum value and which is away from the core and the second clad, toward positions (r1, r3) in contact with the core and the second clad, respectively. The refractive index of the core is higher than the refractive index of the first clad at the position in contact with the core.