Optical Waveguide Adhesive Placement for Thermal Stability
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Solution Overview
Problem
Existing structures connecting optical waveguides and holding parts experience instability and reduction in light propagation due to thermal cycles, with adhesive deterioration and uneven adhesive application causing variations in insertion loss and light amount.
Innovation Solution
A connecting structure is developed where the adhesive is applied in a single region distant from the optical waveguide substrate, with a recess between the adhesive face and the waveguide, preventing adhesive vapor from affecting the optical path and ensuring uniform adhesion, thus stabilizing light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is applied between end faces of optical fiber and optical waveguide to form adhesive layer, then the optical waveguide and holding part can be connected, but the adhesive layer is present in the optical path and may deteriorate under high output power laser heat
Solution Approach 1:
The adhesive layer is extracted from the optical path by positioning it laterally adjacent to the optical waveguide rather than between the optical fiber and waveguide end faces. This removes the adhesive from the direct optical path while maintaining its connection function between the holding part and optical waveguide substrate.
Solution Approach 2:
The adhesive application position is changed from the vertical dimension (between end faces) to the lateral dimension (adjacent to the optical waveguide). This dimensional shift removes the adhesive from the optical path while preserving the mechanical connection.
2Stability of the object's composition
If adhesive is applied in symmetric regions on both sides of optical waveguide substrate, then the connection is balanced, but thermal shock causes uneven stress and adhesive deterioration leading to unstable insertion loss
Solution Approach 1:
The adhesive application structure changes from symmetric (both sides) to asymmetric (single side). The adhesive is applied only in a single region distant from the optical waveguide in the thickness direction, creating an asymmetric configuration that eliminates uneven stress distribution under thermal shock while maintaining connection stability.
3Device complexity
If adhesive is applied close to the optical waveguide substrate, then the connection is compact, but adhesive vapor during curing affects the optical path and deteriorates light intensity
Solution Approach 1:
The adhesive is positioned in another dimension (lateral direction) rather than vertically close to the optical waveguide. This spatial separation in the thickness direction prevents adhesive vapor from affecting the optical path during curing while maintaining a compact overall structure.
Solution Approach 2:
The connection structure is segmented into distinct functional zones: the optical path region and the adhesive application region. This segmentation separates the optical function from the mechanical connection function, preventing interference between them during the curing process.
Data Source
AI summary
A connecting structure includes an optical waveguide part, a holding part of holding an optical input member, and an adhering part adhering the optical waveguide part and holding part. The optical waveguide part includes an optical waveguide substrate including an optical waveguide. At least one of the holding part and optical waveguide part includes a recess and an adhesive face adjacent to the recess. The adhering part is provided on the adhesive face and in a single region distant from the optical waveguide substrate in a direction of thickness of the optical waveguide substrate. The recess is provided between the adhering part and optical waveguide substrate. A space is provided between an end face of the optical input member and an end face of the optical waveguide.