Optical Connector Ferrule Spacer Thermal Expansion Control
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Solution Overview
Problem
Existing optical connector ferrules face issues with increased coupling loss due to eccentricity between optical fibers and lens parts, primarily caused by thermal expansion differences between materials and challenges in submicron positioning.
Innovation Solution
The design incorporates a spacer with a lens part and a base part made of different materials, where the base part is made of the same material as the MT ferrule, ensuring minimal thermal expansion difference (0.5×10−5/°C or less), and the lens part is optically coupled to the MT ferrule, suppressing eccentricity and coupling loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lens plate is made of optical resin without glass filler, then the optical coupling is improved, but the thermal expansion difference increases causing positional displacement
Solution Approach 1:
The ferrule is divided into two separate components: the ferrule main body (made of resin with glass filler for dimensional stability) and the lens plate (made of optical resin for good optical coupling). This segmentation allows each component to be optimized for its specific function while mitigating the thermal expansion issue through separate material selection.
Solution Approach 2:
A positioning structure consisting of positioning protrusions on the ferrule main body and positioning recesses on the lens plate serves as an intermediary mechanism. This positioning structure compensates for thermal expansion differences by providing mechanical alignment that maintains submicron positioning accuracy despite differential thermal expansion between the two materials.
2Ease of manufacture
If the ferrule is made as a one-piece component, then the manufacturing is simplified, but the positioning precision between optical fiber and lens part decreases
Solution Approach 1:
The ferrule is segmented into the ferrule main body and lens plate as separate components that are assembled together. This segmentation enables the lens plate to be precisely positioned using the positioning structure, achieving submicron positioning precision that would be difficult to obtain with a one-piece molded ferrule.
Solution Approach 2:
The positioning structure provides self-aligning and self-positioning functionality during assembly. The positioning protrusions and recesses automatically guide the lens plate into the correct position relative to the ferrule main body, eliminating the need for complex external positioning equipment and achieving high precision through the design itself.
3Reliability
If the lens part is exposed on the bottom surface of the recess, then the non-contact spatial coupling is achieved, but the dust contamination risk increases
Solution Approach 1:
The lens plate is nested within the ferrule assembly, with the lens part exposed in a controlled manner through the recess. The ferrule main body surrounds and protects the lens plate, creating a nested structure that allows the lens to function in non-contact spatial coupling while the surrounding structure provides protection against dust contamination from the external environment.
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 effectively reduces coupling loss by controlling eccentricity between the optical fiber and the lens part, even with temperature changes, while allowing for easy manufacturing and dust protection through spatial coupling and recess design.
Implementation Method 1
a lens part exposed on a bottom surface of the recess, the lens part being optically coupled to the optical end surface of the MT ferrule
Implementation Method 2
a material of the base part and a material of the MT ferrule are the same... a difference between a linear expansion coefficient of the base part and a linear expansion coefficient of the MT ferrule is 0.5×10−5/° C. or less
Data Source
AI summary
An optical connector ferrule according to an embodiment includes an MT ferrule, and a spacer mounted on an optical end surface of the MT ferrule and having a guide hole into which a guide pin is inserted. The spacer has a contact surface that contacting the counterpart connector and a recess surrounded by the contact surface. The spacer includes a lens part exposed on a bottom surface of the recess and optically coupled to the optical end surface of the MT ferrule and a base part that retains the lens part by surrounding the lens part. The material of the lens part and the material of the base part are different from each other, and the difference between the linear expansion coefficient of the base part and the linear expansion coefficient of the MT ferrule is 0.5×10−5/° C. or less.