Photodiode Assembly 3D Stacking Low Cross Talk
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Solution Overview
Problem
Conventional photodiode packaging for submarine networks fails to achieve high isolation performance due to space constraints and limited market availability of high-isolation packaged Indium Gallium Arsenide (InGaAs) photodiodes, necessitating a solution for integrating multiple photodiodes with minimal cross talk in a reduced package size.
Innovation Solution
The integration of multiple photodiodes in a single package with a common carrier, where optical fibers are actively aligned and positioned to minimize cross talk, utilizing a multi-port receiver with PIN diodes and a stair-step arrangement in three dimensions to optimize fiber placement and diode positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple photodiodes are integrated into a single package, then package size is reduced and space constraints are addressed, but cross talk between photodiodes increases and isolation performance deteriorates
Solution Approach 1:
The patent applies three-dimensional stacking arrangement where photodiodes are positioned at different vertical levels (z-axis) rather than only horizontal planes. This dimensional transition allows closer packing while maintaining isolation, as light from one photodiode must travel through multiple layers and absorbing materials to reach adjacent photodiodes, thereby reducing cross-talk while achieving compact packaging.
Solution Approach 2:
The patent introduces intermediate absorbing materials and optical isolation structures between adjacent photodiodes. These intermediary elements absorb stray light and prevent it from reaching neighboring photodiodes, effectively blocking the harmful cross-talk effect while allowing the photodiodes to be positioned in close proximity within the compact package.
2Volume of moving object
If photodiodes are positioned closer together to reduce package size, then space constraints are addressed, but isolation performance between photodiodes deteriorates
Solution Approach 1:
The patent transitions from two-dimensional lateral arrangement to three-dimensional vertical stacking, positioning photodiodes at different heights along the z-axis. This dimensional change enables closer spacing while maintaining isolation performance, as the vertical separation combined with absorbing materials effectively blocks optical interference between adjacent photodiodes in the compact structure.
Solution Approach 2:
The patent implements localized optical isolation measures specifically at the interfaces between adjacent photodiodes, such as positioning absorbing materials in the gaps between photodiode elements. This local quality enhancement ensures that isolation performance is maintained at critical interfaces while allowing overall package size to be reduced through compact three-dimensional arrangement.
3Reliability
If conventional packaging is used with single photodiode per package, then isolation performance is maintained, but space constraints in submarine networks are not addressed
Solution Approach 1:
The patent merges multiple photodiodes that were previously packaged separately into a single integrated package. By combining multiple photodiode elements with their respective optical fibers and interconnection structures into one unified package, the patent achieves space reduction while incorporating design features that maintain the isolation performance previously achieved through separate packaging.
Solution Approach 2:
The patent transitions from horizontal lateral arrangement of separate packages to vertical three-dimensional stacking within a single package. This dimensional change enables multiple photodiodes to be accommodated in a compact volume while maintaining isolation performance through vertical separation and optical isolation materials positioned between the stacked photodiode layers.
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 enables high isolation performance exceeding -40 dB, meeting stringent submarine network requirements while reducing package size, thereby addressing space constraints and market limitations.
Implementation Method 1
a first photo-diode (101) coupled to the first optical fibre (103), a second photo-diode (105) coupled to the second optical fibre (107)
Data Source
AI summary
This disclosure describes a use of cleaved optical fibre and PIN diode placement to reduce optical feedback from a plurality of PIN diodes. The PIN diodes may be separated in two or three dimensions to increase isolation.