Aliphatic Resin Optical Waveguide Core Reducing 850 nm Loss

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Solution Overview

Problem

Optical waveguides for long-distance transmission face limitations in reducing loss due to vibrational absorption at 850 nm caused by aromatic resin skeletons, which conventional methods fail to adequately address.

Innovation Solution

A photosensitive resin composition with a resin component having an absorbance of less than 0.03 at 2960 cm−1, incorporating a polymerizable substituent-containing aliphatic resin structure to minimize C—H bond vibrational absorption, thereby reducing loss at 850 nm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If an aromatic resin component is used in the core layer formation material, then the refractive index is improved (higher than cladding layer), but the absorption loss at 850 nm increases due to broadening of the fourth harmonic absorption peak

Engineering Contradiction:
Improverefractive indexVSAvoidabsorption loss at 850 nm
Core Design Contradiction:
Illumination intensityVSLoss of energy

Solution Approach 1:

The patent changes the chemical structure parameter of the resin from aromatic to aliphatic type, specifically selecting resins with absorbance at 2960 cm−1 of 0.05 or less. This parameter change eliminates the fourth harmonic absorption peak broadening issue while maintaining the necessary refractive index for optical waveguide functionality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by specifying particular aliphatic resin structures with low absorbance characteristics at the critical 2960 cm−1 wavelength region. Instead of using a generic resin type, it selects resins with specific molecular structures that locally minimize absorption at the 850 nm transmission wavelength while maintaining overall optical waveguide performance.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the purity of the resin component is improved, then the transparency is enhanced, but the absorption peak still broadens to 850 nm due to the aromatic skeleton structure

Engineering Contradiction:
ImprovetransparencyVSAvoidabsorption loss at 850 nm
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The patent fundamentally changes the chemical composition parameter from aromatic to aliphatic resin structure. Even with high purity aliphatic resins, the absorption peak broadening issue is eliminated because the molecular structure itself (aliphatic vs aromatic) determines the absorption characteristics, not just the purity level.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If the amount of photopolymerization initiator is reduced, then the absorption loss is decreased, but the curing efficiency and manufacturing process becomes more difficult to control

Engineering Contradiction:
Improveabsorption lossVSAvoidcuring process control
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent changes the resin structure parameter to aliphatic type with specific absorbance characteristics, which intrinsically reduces absorption loss at 850 nm. This structural change allows for better control of the photopolymerization process while maintaining low loss, as the resin matrix itself contributes less to absorption rather than relying solely on reducing initiator content.

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 effectively reduces absorption loss at 850 nm, enhancing the transparency and efficiency of optical waveguides for long-distance transmission by using an aliphatic resin structure instead of aromatic, resulting in improved performance for hybrid flexible printed wiring boards.

Implementation Method 1

the resin component includes a polymerizable substituent-containing resin as a main component

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

the peak of fourth harmonic absorption (aromatic 4vCH) attributable to the vibrational absorption of a C—H bond of an aromatic ring

Methodology Applied
Scientific EffectVibrational absorption: Absorption (EM radiation)

Data Source

PatentUS9963541B2Photosensitive resin composition for optical waveguide, photocurable film for formation of optical waveguide core layer, optical waveguide produced by using the resin composition or the photocurable film, and hybrid flexible printed wiring board for optical/electrical transmission
Publication Date: 2018.05.08 NITTO DENKO CORP

AI summary

According to the present invention, a photosensitive resin composition for an optical waveguide contains a resin component and a photopolymerization initiator. The resin component has an absorbance of less than 0.03 as measured at 2960 cm−1 by an attenuated total reflection measurement (ATR) method by means of a Fourier transform infrared spectrophotometer (FT-IR), and includes a polymerizable substituent-containing resin as a main component. Where the inventive optical waveguide photosensitive resin composition is used as a material for the optical waveguide, particularly as a core layer formation material for the optical waveguide, it is possible to reduce a loss, for example, by avoiding vibrational absorption occurring at an optical waveguide transmission light wavelength of 850 nm due to a resin skeleton.