Optical Side I/O Circuit with Grating-Based Wavelength Selectivity

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Solution Overview

Problem

Conventional wavelength multiplexing couplers are large in size and have significant reflection and loss at connecting points, making them difficult to deploy at multiple points in a transmission path. Additionally, while tap waveguides can be easily disposed at multiple points, they lack wavelength selectivity.

Innovation Solution

An optical side input/output circuit with a tap waveguide that includes a grating portion with a long-period fiber grating, providing wavelength selectivity and allowing for easy deployment at multiple points in a transmission path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a wavelength multiplexing coupler is used to achieve wavelength selectivity, then wavelength selectivity is improved, but device size increases and reflection/loss at connecting points increases

Engineering Contradiction:
Improvewavelength selectivityVSAvoiddevice size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent embeds the wavelength multiplexing function within the optical fiber core itself by forming a grating structure directly in the fiber. This nesting approach integrates the coupler functionality into the existing fiber infrastructure, eliminating the need for separate external coupler devices and reducing overall device size while maintaining wavelength selectivity

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent replaces traditional mechanical wavelength multiplexing couplers with an all-optical grating-based solution written directly in the fiber. This substitution eliminates mechanical connecting points and associated reflection/loss issues while achieving the same wavelength selective functionality through optical interference effects in the grating structure

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a wavelength multiplexing coupler is used to achieve wavelength selectivity, then wavelength selectivity is improved, but reflection and loss at connecting points increase

Engineering Contradiction:
Improvewavelength selectivityVSAvoidreflection and loss at connecting points
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent replaces mechanical wavelength multiplexing couplers with an all-optical grating-based solution written directly in the fiber. This substitution eliminates mechanical connecting points and associated reflection/loss issues while achieving the same wavelength selective functionality through optical interference effects in the grating structure

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent merges the wavelength multiplexing function with the optical fiber transmission medium by forming the grating structure directly within the fiber core. This integration combines the coupler functionality with the transmission path, eliminating separate connecting points and reducing reflection and energy loss

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a tap waveguide is used to enable easy disposal at multiple points, then ease of deployment is improved, but wavelength selectivity is lost

Engineering Contradiction:
Improveease of deploymentVSAvoidwavelength selectivity
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent creates a multi-functional structure where the optical fiber simultaneously serves as the transmission medium and the wavelength selective element. The grating structure written in the fiber provides both the tap waveguide functionality for easy deployment and the wavelength multiplexing selectivity, making the system universally applicable without sacrificing either ease of deployment or wavelength discrimination

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Ease of operation

If conventional tap waveguides are used to enable easy disposal at multiple points, then ease of deployment is improved, but wavelength selectivity decreases

Engineering Contradiction:
Improveease of deploymentVSAvoidwavelength selectivity
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent creates a multi-functional structure where the optical fiber simultaneously serves as the transmission medium and the wavelength selective element. The grating structure written in the fiber provides both the tap waveguide functionality for easy deployment and the wavelength multiplexing selectivity, making the system universally applicable without sacrificing either ease of deployment or wavelength discrimination

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 optical side input/output circuit achieves wavelength selectivity and can be easily disposed at multiple points in a transmission path, enabling efficient light input/output of desired wavelengths while minimizing loss.

Implementation Method 1

a grating portion 20 that is located in a stage before the tap portion 10 in the propagation direction of the light, and has a grating 21 that converts light of a desired wavelength from a basic mode to the higher-order mode

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

a tap portion 10 in which a tap waveguide 53 that outputs light of a higher-order mode from a side surface of an optical fiber 50 is formed

Methodology Applied
Scientific EffectOptical waveguide coupling: Waveguide (optics)

Data Source

PatentEP4215962B1Optical side input/output circuit and optical connector
Publication Date: 2025.02.12 NT T INC
  • EP4215962B1 patent drawingFigure 1
  • EP4215962B1 patent drawingFigure 2
  • EP4215962B1 patent drawingFigure 3

AI summary

The present invention aims to provide an optical side input/output circuit that has wavelength selectivity and is easily disposed at multiple points in a transmission path, and an optical connector. The optical side input/output circuit 301 includes: a tap portion 10 in which a tap waveguide 53 that outputs light of a higher-order mode from a side surface of an optical fiber 50 is formed, the light of the higher-order mode being of light propagating in the core 51 of the optical fiber 50; and a grating portion 20 that is located in a stage before the tap portion 10 in the propagation direction of the light, and has a grating 21 that converts light of a desired wavelength from a basic mode to the higher-order mode, the grating 21 being formed in the core 51 of the optical fiber 50.