Passive Fiber Alignment in Backplane Optical Interconnect Cards
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Solution Overview
Problem
Current high-performance opto-electronic systems face challenges in achieving a ten-fold increase in interconnection bandwidth every four years while maintaining minimal cost, power, and space requirements, with 2.5/3D IC packaging and silicon photonics, but struggle with scalable configurations for large numbers of high-bandwidth interconnects.
Innovation Solution
A high-density, backplane-pluggable interconnection card with electrical connections along one edge and optical fibers for the rest, utilizing on-board optical sources and silicon photonic-based circuitry, along with passively aligned fiber arrays for I/O connections, and silicon photonic integrated circuits for signal conversion, enabling 19.2 - 76.8 Tb/s bandwidth in each direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 2.5/3D IC packaging and silicon photonics are used to increase interconnection bandwidth, then bandwidth increases, but cost and power consumption increase
Solution Approach 1:
The patent transitions from planar 2D interconnection layouts to three-dimensional vertical stacking with multiple layers (first and second optical interconnection layers) connected via through-silicon vias. This dimensional change enables higher bandwidth by increasing interconnection density without proportionally increasing footprint area or component count, thereby improving productivity while controlling manufacturing complexity
Solution Approach 2:
The patent implements nested integration by placing optical interconnection layers within and between semiconductor substrates. The first optical interconnection layer is formed within a first substrate, the second optical interconnection layer is formed within a second substrate, and these are vertically stacked and connected. This nesting approach increases bandwidth capacity while containing components within compact volumetric boundaries, preventing cost escalation from excessive space requirements
2Productivity
If 2.5/3D IC packaging and silicon photonics are used to increase interconnection bandwidth, then bandwidth increases, but power consumption increases
Solution Approach 1:
The patent replaces electrical signal transmission through copper interconnects with optical signal transmission through waveguides and optical fibers. This substitution eliminates resistive heating losses associated with electrical conductors, reducing power consumption while enabling higher bandwidth. The optical interconnection layers use photonic waveguides to transmit data as light signals, fundamentally changing the energy transmission mechanism
Solution Approach 2:
By implementing vertical stacking of optical interconnection layers through three-dimensional integration, the patent reduces the need for long horizontal electrical traces that consume significant power. The short vertical optical paths through the stacked substrates minimize energy loss and reduce overall power consumption while achieving high bandwidth through increased interconnection density
3Productivity
If large numbers of high bandwidth interconnects are implemented, then bandwidth increases, but device complexity increases
Solution Approach 1:
The patent divides the optical interconnection system into distinct functional segments: first optical interconnection layer within first substrate, second optical interconnection layer within second substrate, through-silicon vias for inter-layer connection, and separate coupling mechanisms. This segmentation allows each component to be independently designed, fabricated, and tested, reducing overall system complexity while enabling high bandwidth through modular scalability
Solution Approach 2:
The patent employs universal through-silicon via structures that serve multiple functions: providing mechanical support between layers, enabling optical signal transmission, and facilitating electrical biasing. The waveguide structures also serve dual purposes as both signal carriers and alignment references. This multi-functionality reduces the number of separate components needed, simplifying the configuration while maintaining high bandwidth capability
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 solution provides a scalable, high-density interconnection configuration that supports high bandwidth while minimizing cost, power, and space, achieving efficient optical I/O bandwidth through passive alignment and silicon photonic integration.
Implementation Method 1
a silicon photonic integrated circuit (PIC) disposed on the package substrate and used to provide conversion between optical input signals and electrical output signals
Implementation Method 2
a plurality of passively-aligned optical fiber array connectors coupled between the at least one laser transmitter module and the silicon PIC
Data Source
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AI summary
A high density interconnect arrangement takes the form of a backplane-pluggable card, with electrical connections formed along a single (pluggable) edge and all remaining connections provided via optical fibers. An exemplary interconnect arrangement also includes on-board optical sources and silicon photonic-based circuitry for providing optical transceiver functionality. Passively aligned fiber arrays are utilized to provide I/O connections to external elements, as well as between laser sources and on-board silicon photonics.