Faraday Rotator Optical Interconnects for Semiconductor Packaging
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Solution Overview
Problem
Direct optical coupling between an optical cable and a photonics die in electronic packages leads to low signal-to-noise ratios due to reflections at the interface, resulting in optical interference and inaccurate signal propagation.
Innovation Solution
Integration of a Faraday rotator between the optical cable and the photonics die, which comprises a polarizer, a magnetic region, and another polarizer, to filter out reflections and improve signal quality by shifting the polarization of light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct optical coupling is used between optical cable and photonics die, then the coupling architecture is simple, but the signal-to-noise ratio deteriorates due to reflections and optical interference
Solution Approach 1:
A Faraday rotator is introduced as an intermediary component between the optical cable and the photonics die. This mediator device rotates the polarization of incident light by 45 degrees, which eliminates reflected light at the interface and prevents optical interference, thereby improving the signal-to-noise ratio while maintaining a relatively simple coupling architecture
Solution Approach 2:
The patent converts the harmful effect of polarization reflections into a beneficial outcome. By introducing the Faraday rotator that rotates polarization by 45 degrees, the reflected light that would normally cause interference is transformed into a non-interfering component, converting the harmful reflection effect into a benefit for improving signal quality
2Device complexity
If direct optical coupling is used, then the device structure is simple, but optical interference increases and signal accuracy decreases
Solution Approach 1:
The Faraday rotator serves as a mediating component that rotates the polarization state of light by 45 degrees. This polarization rotation ensures that reflected light does not interfere with the incident light, thereby maintaining signal accuracy and eliminating optical interference while keeping the device structure relatively simple
Solution Approach 2:
The patent changes the polarization parameter of the incident light by 45 degrees through the Faraday rotator. This parameter change fundamentally alters the interference condition at the interface, transforming the system from one that generates optical interference to one that eliminates it, thereby improving signal accuracy
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 ensuring accurate signal propagation.
Implementation Method 1
a Faraday rotator between an optical cable and the photonics die... Integration of a Faraday rotator between the optical cable and the photonics die, which comprises a polarizer, a magnetic region, and another polarizer, to filter out reflections and improve signal quality by shifting the polarization of light
Data Source
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AI summary
Embodiments disclosed herein include photonics package with Faraday rotators to improve efficiency. In an embodiment, a photonics package comprises a package substrate and a compute die over the package substrate. In an embodiment, the photonics package further comprises a photonics die over the package substrate. In an embodiment, the compute die is communicatively coupled to the photonics die by a bridge in the package substrate. In an embodiment, the photonics package further comprises an integrated heat spreader (IHS) over the package substrate, and a Faraday rotator passing through the IHS and optically coupled to the photonics die.