Vertical Edge Coupler for Multi-Chip Optical Interconnects
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Solution Overview
Problem
Existing multi-chip modules face challenges with high optical losses and sensitivity to alignment variations due to divergent optical signals and complex optical path lengths in optical coupling between chips, impacting the performance of macrochips.
Innovation Solution
A multi-chip module design featuring optical waveguides with vertically displaced facets and tapers, facilitating direct optical coupling with larger spatial modes and alignment features to reduce optical losses and misalignment risks, implemented using silicon-on-insulator technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If face-to-face optical proximity couplers are used to couple optical signals between chips, then optical coupling can be achieved, but optical losses increase and coupling fidelity decreases due to divergent optical signals and long optical path lengths
Solution Approach 1:
The patent transitions from horizontal face-to-face coupling to vertical edge-to-edge coupling by changing the spatial dimension of the optical path. Optical signals are coupled between vertically stacked chips through edge facets, eliminating the need for out-of-plane reflection and reducing optical path length and divergence.
Solution Approach 2:
The patent extracts and eliminates the intermediate horizontal propagation path and out-of-plane reflection components from the optical coupling system. By directly coupling edge facets vertically, it removes the sources of optical divergence and path length issues.
2Reliability
If face-to-face optical proximity couplers with out-of-plane reflection are used, then optical coupling between chips is enabled, but sensitivity to alignment variations increases
Solution Approach 1:
The patent changes the coupling geometry from horizontal face-to-face to vertical edge-to-edge, simplifying the optical path and reducing alignment sensitivity by eliminating out-of-plane reflection requirements.
Solution Approach 2:
Instead of reflecting light out of the plane and back in, the patent inverts the approach by directly coupling light between vertical edges, reversing the optical path geometry to achieve simpler alignment requirements.
3Length of stationary object
If optical signals are reflected out of the plane at specific angles, then optical coupling between chips is achieved, but optical path length increases causing signal divergence
Solution Approach 1:
The patent extracts and removes the unnecessary out-of-plane reflection segments from the optical path, creating a direct vertical coupling path between edge facets that minimizes optical path length and prevents signal divergence.
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 design achieves high-fidelity signaling with low-loss coupling and broadband transmission, improving performance by reducing optical path length and divergence, thus enhancing macrochip functionality.
Implementation Method 1
the first optical coupler has a first optical mode that is different than a second optical mode associated with the first optical waveguide
Implementation Method 2
the second vertical facet is horizontally displaced relative to and faces the first vertical facet, thereby facilitating direct optical coupling of an optical signal from the first vertical facet to the second vertical facet
Data Source
AI summary
In an MCM, an optical signal is conveyed by an optical waveguide disposed on a surface of a first substrate to an optical coupler having a vertical facet. This optical coupler has an optical mode that is different than the optical mode of the optical waveguide. For example, the spatial extent of the optical mode associated with the optical coupler may be larger, thereby reducing optical losses and sensitivity to alignment errors. Then, the optical signal is directly coupled from the vertical facet to a facing vertical facet of an identical optical coupler on another substrate, and the optical signal is conveyed in another optical waveguide disposed on the other substrate.