Coherent Fiber Bundle Optical Links for Dense Chiplet Interconnects
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Solution Overview
Problem
The limitations of chip-to-chip connections in integrated circuits (ICs) include increased power consumption and reduced density due to the use of chiplets, and the high cost and limited density of optical links dominated by coupling optical sources and detectors to waveguides, particularly in data communication applications.
Innovation Solution
The use of coherent fiber bundles (CFBs) with microLEDs as optical transmitters and photodetectors, integrated within a multichip module, to create high-density, low-power optical links for chip-to-chip interconnects, utilizing coherent fiber bundles to maintain spatial coherence and reduce crosstalk through optimized optical coupling and alignment techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chiplets are used to de-integrate SoCs, then functionality can be optimized per chiplet and yield increases, but chip-to-chip connections require far more power and have reduced density
Solution Approach 1:
The patent replaces electrical chip-to-chip connections with optical connections using microLEDs and coherent fiber bundles. This substitution eliminates the need for dense electrical interconnects, thereby reducing power consumption per bit while maintaining high data rates. The optical link uses microLEDs as transmitters and photodetectors as receivers, with coherent fiber bundles carrying multiple channels simultaneously.
Solution Approach 2:
The patent transitions from two-dimensional electrical traces on a chip to three-dimensional optical coupling using fiber bundles. By using coherent fiber bundles with multiple cores, the system achieves high-density parallel optical links that can be coupled to microLED arrays, enabling simultaneous transmission of multiple data channels through a single compact component.
2Power
If conventional optical links use waveguide coupling, then optical transmission is achieved, but cost and density are limited by coupling complexity
Solution Approach 1:
The patent segments the optical link into discrete, independently coupleable units: microLEDs for transmission, photodetectors for reception, and individual fiber cores as channels. This segmentation allows each component to be optimized independently and simplifies the coupling process compared to monolithic waveguide systems. The coherent fiber bundle acts as a modular interface between the microLED array and photodetector array.
Solution Approach 2:
The patent changes the coupling parameters by using microLEDs with specific beam characteristics and matching them to fiber cores with appropriate numerical apertures and modes. By optimizing the spatial and angular parameters of the microLED emission and fiber reception, the system achieves efficient coupling without complex waveguide structures. The coherent fiber bundle maintains spatial coherence to enable precise coupling.
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 approach enhances data communication density and reduces power consumption by leveraging microLEDs and coherent fiber bundles, providing efficient and cost-effective optical interconnects for high-performance computing applications.
Implementation Method 1
Optical interconnects based on microLED (uLED) sources may offer a way to overcome some or all of these limitations. A microLED may be generally defined as a LED with a diameter of 1 m at >1 Gbps with lower drive power and very high density.
Implementation Method 2
In some embodiments the optical receiver comprises a photodetector.
Implementation Method 3
Coherent fiber bundles (CFBs) comprised of large numbers of tightly packed fibers are typically used in imaging and illumination applications. However, their unique properties are well-suited to overcoming cost and density issues in short, highly parallel optical links for chip-to-chip interconnects.
Data Source
AI summary
A coherent fiber bundle may be used to optically connect an array of microLEDs to an array of photodetectors in an optical communication system.