Ridge Waveguide Bonding with Flat Overclad to Prevent Air Bubbles
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Solution Overview
Problem
The manufacturing method for wavelength conversion devices results in air bubbles mixing into the overclad and upper adhesive layer, leading to poor appearance and reduced strength due to uneven adhesion and stress on the internal structure.
Innovation Solution
A method involving the formation of groove portions on a non-linear optical material substrate, covering them with a low-refractive index layer, and polishing to create a flat surface for bonding, thereby avoiding air bubbles and ensuring strong adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the overclad is formed to cover the ridge grooves, then the waveguide structure is complete, but air bubbles mix into the adhesive layer causing poor appearance and reduced strength
Solution Approach 1:
The patent applies preliminary action by forming the overclad layer to cover the ridge grooves before applying the adhesive layer. This sequence prevents air from being trapped between the overclad and substrate, as the covering is already in place to guide adhesive flow smoothly without creating air bubble pockets.
Solution Approach 2:
The overclad layer serves as an intermediary element between the ridge grooves and the adhesive layer. By introducing this intermediate structure, the patent eliminates direct contact issues between adhesive and grooves, allowing the adhesive to flow uniformly over the covered surface without trapping air.
2Strength
If the adhesive layer is applied over the overclad, then bonding is achieved, but adhesion drops due to air bubbles creating non-contact portions
Solution Approach 1:
The overclad is formed in advance to create a continuous covering surface before adhesive application. This preliminary structure ensures that when adhesive is applied, it maintains uniform contact with the substrate across the entire bonding area, eliminating non-contact portions that would reduce adhesion reliability.
3Ease of manufacture
If the adhesive layer is applied directly, then bonding process is simple, but the layer becomes uneven causing stress on internal structure
Solution Approach 1:
The overclad layer acts as an intermediary surface that receives the adhesive. This intermediate structure provides a uniform base that guides adhesive flow evenly, preventing the formation of uneven thickness variations that would otherwise create stress concentrations in the internal structure.
Data Source
AI summary
A method of manufacturing a waveguide device includes: forming, in a first surface of a non-linear optical material substrate, a plurality of groove portions so that one groove portion is spaced apart from another groove portion, and configuring, as a ridge waveguide, at least one of portions of the non-linear optical material substrate that are located between groove portions adjacent to each other; forming, on the first surface of the non-linear optical material substrate, a first low-refractive index layer which has a thickness greater than a depth of the groove portions, so that the ridge waveguide is covered; polishing the first low-refractive index layer from an opposite side from the non-linear optical material substrate to render a surface of the first low-refractive index layer a flat surface; and bonding a first support substrate to the flat surface of the first low-refractive index layer.