Silicone Waveguide Composition for Low Loss and Heat Resistance
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Solution Overview
Problem
Current materials for optical waveguides, particularly in the long wavelength range, suffer from high propagation loss and lack heat resistance above 300°C, and there is a scarcity of materials that can effectively produce graded-index (GI) optical waveguides with these properties.
Innovation Solution
A composition combining a reactive silicone compound and a di(meth)acrylate compound, specifically a polycondensate of a diarylsilicic acid compound and an alkoxy silicon compound, is used to create an optical waveguide with high heat resistance and low propagation loss, enabling the fabrication of both multimode and single-mode GI optical waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials (hydrocarbon or epoxy group compounds) are used for optical waveguides, then propagation loss in long wavelength range increases, but heat resistance remains insufficient
Solution Approach 1:
The patent employs a composite material system comprising a silicone-based polymer matrix combined with specific photopolymerizable groups (acrylate, methacrylate, or vinyl groups). This composite structure allows the material to simultaneously achieve high heat resistance (maintaining mechanical properties above 300°C) from the silicone backbone and low propagation loss in long wavelength range (1310nm and 1550nm) through the optimized polymerizable groups and curing mechanism.
2Ease of manufacture
If step-index (SI) structure is used for optical waveguide, then manufacturing processability is improved, but crosstalk occurs with narrow pitch cores
Solution Approach 1:
The patent applies local quality by creating a graded-index (GI) structure where the refractive index varies continuously from the core center to the cladding interface. This is achieved by controlling the concentration gradient of photopolymerizable groups or crosslinking density during curing, resulting in higher refractive index at the core center and gradually decreasing index toward the cladding. This local variation in optical properties confines light more effectively to the core center, eliminating crosstalk between adjacent narrow-pitch cores while maintaining manufacturing feasibility through single-step coating and curing processes.
3Object-generated harmful factors
If graded-index (GI) structure is used for optical waveguide, then crosstalk is eliminated, but manufacturing difficulty increases
Solution Approach 1:
The patent merges the core material and cladding material into a single homogeneous composition before curing. The composition contains a silicone-based polymer and photopolymerizable groups in specific ratios, where the photopolymerizable groups are distributed throughout the entire material. During a single coating and curing step, the material forms a graded-index structure through self-organization or controlled diffusion, eliminating the need for separate core and cladding deposition processes. This merging approach simplifies manufacturing while achieving the desired GI profile that prevents crosstalk.
Solution Approach 2:
The patent incorporates photopolymerizable groups (acrylate, methacrylate, or vinyl) and crosslinking agents into the silicone-based polymer matrix before coating. This preliminary preparation ensures that the material is pre-configured with the necessary chemical components to form the graded-index structure during curing. The pre-mixed composition allows for controlled refractive index gradient formation through uniform initial distribution of reactive groups, which then undergo polymerization to create the desired optical profile in a single processing step, greatly simplifying fabrication.
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 resulting optical waveguide exhibits excellent optical characteristics, including high refractive index and low propagation loss in the long wavelength band, with heat resistance suitable for opto-electronic circuit boards and the ability to produce GI waveguides that are difficult to fabricate with conventional materials.
Implementation Method 1
Light is applied to a coating film of this resin to induce mass diffusion of the photolyte and the photocurable epoxy compound
Implementation Method 2
In the SI structure, a core and cladding define a clear interface between refractive indices, and reflection at the interface allows light to propagate
Data Source
Figure 1~2
Figure 3(a)~6(d)
Figure 7~9
AI summary
There is provided an optical waveguide-forming composition that has high heat resistance and low light propagation loss in the long wavelength range and can obtain a GI optical waveguide. The optical waveguide-forming composition comprising: 100 parts by mass of a reactive silicone compound (a) composed of a polycondensate of a diarylsilicic acid compound A of Formula [1] wherein Ar1 and Ar2 are a phenyl group, a naphthyl group or a biphenyl group optionally substituted, and an alkoxy silicon compound B of Formula [2] Ar3-Si(OR1)aR23-a [2] wherein Ar3 is a phenyl group, a naphthyl group or a biphenyl group having at least one group having a polymerizable double bond, R1 is methyl group or ethyl group, R2 is methyl group, ethyl group, or vinylphenyl group, and a is 2 or 3, and 1 part by mass to 200 parts by mass of a di(meth)acrylate compound (b) of Formula [3] wherein R3 and R4 are a hydrogen atom or methyl group, R5 is a hydrogen atom, methyl group, or ethyl group, L1 and L2 are an alkylene group, and m and n are 0 or a positive integer, wherein m+n is 0 to 20.