Optical Ferrule Alignment During Thermal Expansion

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Solution Overview

Problem

Existing optical connector solutions for photonic integrated circuits (PICs) face challenges in efficiently coupling light between optical fibers and small-core PIC waveguides, due to high costs, slow alignment processes, and high loss rates.

Innovation Solution

The development of an optical ferrule with a light redirecting member that permanently attaches to multiple optical fibers, redirecting light along a different direction for optimal alignment and coupling, along with a cradle system that minimizes thermal expansion-induced misalignment through constraint members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active alignment of fibers is performed to achieve efficient light coupling, then coupling efficiency is improved, but manufacturing cost and time increase

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidalignment speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs active alignment and permanent attachment of fibers to the ferrule in advance during manufacturing. The ferrule is pre-aligned with the PIC waveguide and fibers are permanently fixed in this position, eliminating the need for time-consuming alignment during field deployment or installation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a permanent mechanical copy of the alignment relationship through the rigid ferrule structure. The ferrule maintains the precise spatial relationship between fibers and waveguide through its rigid construction and engagement features, replicating the aligned position without requiring active adjustment mechanisms during operation.

Inventive Principle:

Principle #26Copying

2Reliability

If permanent attachment of fibers to ferrule is implemented, then assembly reliability is improved, but alignment precision during assembly becomes more difficult

Engineering Contradiction:

Improveattachment reliabilityVSAvoidalignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The ferrule serves as an intermediary component that mechanically couples the flexible optical fibers to the rigid PIC substrate. It provides a stable mounting structure with engagement features that secure fibers in precise positions relative to the waveguide, translating the alignment requirement into a mechanical fitting problem that is easier to control during manufacturing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If ferrule structure is made rigid for stable light redirection, then optical alignment is improved, but thermal expansion mismatch with substrate increases

Engineering Contradiction:

Improvealignment stabilityVSAvoidthermal expansion mismatch

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies different material properties to different parts of the system. The ferrule body is made rigid for stable light redirection, while the engagement features and mounting structures use materials or designs that accommodate thermal expansion. This allows the critical optical path to remain stable while the mounting interface absorbs dimensional changes.

Inventive Principle:

Principle #3Local quality

4Reliability

If light redirecting member is added to change light direction, then coupling to PIC waveguide is improved, but device complexity increases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidferrule structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the light redirecting function with the mechanical mounting structure of the ferrule. The light redirecting member is integrated into the ferrule body or as a permanent component within it, eliminating the need for separate alignment mechanisms or adjustable components. This merging reduces the number of parts and simplifies the overall assembly while maintaining effective light coupling.

Inventive Principle:

Principle #5Merging (Combining)

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 solution enables efficient, cost-effective, and low-loss light coupling between optical fibers and PIC waveguides, maintaining alignment across varying temperatures due to the cradle's constraint members.

Implementation Method 1

A light redirecting member of the ferrule receives light, along a first direction, from a plurality of fibers received by and permanently attached to the attachment area and redirects the received light along a different second direction

Methodology Applied

Scientific EffectLight redirection: Reflection

Implementation Method 2

Apparatus and method for maintaining optical ferrule alignment during thermal expansion or contraction

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

Apparatus and method for maintaining optical ferrule alignment during thermal expansion or contraction

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS12242119B2Apparatus and method for maintaining optical ferrule alignment during thermal expansion or contraction

Publication Date: 2025.03.04 3M INNOVATIVE PROPERTIES CO

AI summary

An optical ferrule has a different thermal expansion coefficient than a substrate to which a optical device is mounted, the ferrule optically coupling the device to one or more optical fibers. The optical ferrule includes and/or a cradle in which the ferrule is mounted include lateral and longitudinal engagement feature that ensure alignment with the optical device at an operating temperature, the ferrule expanding relative to the substrate when transitioning to the operating temperature.