Optical Waveguide Adhesive Refractive Index Matching
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Solution Overview
Problem
The interposition of an adhesive layer between the exposed cores of two optical waveguides leads to increased optical coupling loss due to light leakage through the adhesive layer, which has a refractive index closer to that of the cores.
Innovation Solution
An optical waveguide device is designed with an adhesive layer that adheres the waveguides to each other, with the adhesive layer filled between the claddings and having a refractive index closer to that of the claddings than to that of the cores, thereby minimizing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer is interposed between the exposed surfaces of the cores of two optical waveguides to achieve adhesion, then the waveguides can be coupled together, but light movement between the cores is obstructed and optical coupling loss is increased
Solution Approach 1:
The patent introduces a cladding layer as an intermediary between the adhesive layer and the core surfaces. This cladding layer has a refractive index that is closer to the core refractive index than the adhesive layer's refractive index, creating a gradual refractive index transition that reduces light leakage while maintaining the adhesive layer's bonding function.
Solution Approach 2:
The patent changes the refractive index parameter of the cladding layer to be closer to the core refractive index (n_core < n_cladding < n adhesive) compared to the adhesive layer alone. This parameter adjustment creates a more favorable optical path that reduces light loss while preserving adhesion.
2Strength
If the refractive index of the adhesive layer is adjusted to be closer to the refractive index of the cores to improve adhesion, then bonding is enhanced, but light leaks out from the optical waveguides via the adhesive layer and optical coupling loss is increased
Solution Approach 1:
The cladding layer serves as a mediator that bridges the refractive index difference between the adhesive layer and the core. By positioning the cladding layer's refractive index between those of the adhesive layer and core, it gradually transitions the refractive index profile, reducing abrupt changes that cause light leakage while maintaining effective adhesion through the adhesive layer.
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 configuration reduces optical coupling loss between the adhered optical waveguides by minimizing light leakage through the adhesive layer, enhancing the efficiency of light transmission.
Implementation Method 1
an adhesive layer that adheres the first optical waveguide and the second optical waveguide to each other
Implementation Method 2
the adhesive layer has a refractive index closer to refractive indexes of the first cladding and the second cladding than to refractive indexes of the first core and the second core
Data Source
AI summary
An optical waveguide device has a first optical waveguide, a second optical waveguide, and an adhesive layer. The first optical waveguide has: a first cladding; and a first core having a distal end portion exposed from the first cladding. The second optical waveguide has: a second cladding; and a second core having a distal end portion exposed from the second cladding. The adhesive layer adheres the first optical waveguide and the second optical waveguide in a state where the distal end portions of the first core and of the second core have been arranged to partially overlap each other. The adhesive layer covers lateral surfaces of the distal end portions of the first core and of the second core and has a refractive index closer to refractive indexes of the first cladding and the second cladding than to refractive indexes of the first core and the second core.