Faraday Rotator Through-Via Interconnect for Cleaner Photonics Coupling

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Solution Overview

Problem

Direct optical coupling between an optical cable and a photonics die in electronic packages results in low signal-to-noise ratios due to reflected light and optical interference, leading to inaccurate signal propagation.

Innovation Solution

Integration of a Faraday rotator between the optical cable and the photonics die, which uses a magnetic region to shift the polarization of light, thereby filtering out reflections and improving signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If direct optical coupling is used between optical cable and photonics die, then device complexity is reduced, but signal-to-noise ratio deteriorates due to reflected light and optical interference

Engineering Contradiction:

Improvecoupling architecture complexityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A Faraday rotator is introduced as an intermediary component between the optical cable and photonics die. This rotator uses the Faraday effect (magneto-optic rotation) to rotate the polarization of light by 45 degrees, enabling the optical signal to pass through while blocking reflected light that returns with different polarization states, thereby improving signal-to-noise ratio without significantly increasing overall device complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the polarization parameter of light using a Faraday rotator. By rotating the polarization angle of incoming light and exploiting polarization-dependent reflection characteristics, the system achieves better signal quality. The through-via structure also changes the spatial parameter by creating a vertical optical path through the substrate

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a Faraday rotator is integrated into the optical path, then signal-to-noise ratio is improved, but device complexity increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidcoupling architecture complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The Faraday rotator is merged with the substrate structure by integrating it into a through-via configuration. The rotator, magnetic material, and optical path are combined into a single vertical stack within the substrate, eliminating the need for separate discrete components and reducing overall device complexity while maintaining signal-to-noise ratio improvements

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The Faraday rotator components (magnetic material, optically clear material, polarizing filters) are nested within the substrate's through-via structure. The magnetic material is positioned at specific depths within the via, with optically clear material filling surrounding spaces, creating a compact nested arrangement that minimizes device footprint and complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

3Object-generated harmful factors

If through-via configuration with Faraday rotator is used, then optical interference is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveoptical interferenceVSAvoidvia alignment and material placement precision

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The magnetic material is positioned and secured in the through-via before final optical assembly steps. By pre-placing the magnetic material at the correct depth and orientation, the subsequent alignment of optical components becomes simpler, reducing the overall manufacturing precision requirements despite the complex multi-material structure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies different materials with specific local properties at different positions within the through-via. The magnetic material is placed only where the magnetic field is needed for the Faraday effect, while optically clear material fills other spaces. This localized material distribution reduces manufacturing complexity compared to uniform structures

Inventive Principle:

Principle #3Local quality

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

The implementation of a Faraday rotator significantly enhances the signal-to-noise ratio and improves the performance of optical interconnects by reducing optical interference and reflections.

Implementation Method 1

a Faraday rotator between the optical cable and the photonics die, which uses a magnetic region to shift the polarization of light

Methodology Applied

Scientific EffectFaraday effect: Faraday Effect

Data Source

PatentEP4016151B1Faraday rotator interconnect as a through-via configuration in a patch architecture

Publication Date: 2025.04.16 INTEL CORP

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AI summary

Embodiments disclosed herein include optical systems with Faraday rotators in order to enhance efficiency. In an embodiment, a photonics package comprises an interposer and a patch over the interposer. In an embodiment, the patch overhangs an edge of the interposer. In an embodiment, the photonics package further comprises a photonics die on the patch and a Faraday rotator passing through a thickness of the patch. In an embodiment, the Faraday rotator is below the photonics die.