Edge-Coupled Optical Proximity Communication Module
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Solution Overview
Problem
Existing optical modules face challenges in achieving low-loss edge-to-edge optical coupling due to mode mismatch and increased complexity and cost, especially when using face-up and face-down chips with optical waveguides on silicon substrates, which require precise alignment and are prone to disturbances like thermal expansion and vibration.
Innovation Solution
An optical module design that includes an alignment substrate mechanically coupled to optical devices, aligning edges and optical components for perpendicular optical coupling, potentially using mode converters for sub-micron waveguides to reduce losses, and utilizing a single type of chip with optical components on one side to simplify integration and reduce packaging complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If face-up and face-down chips are used for optical coupling, then optical signal transmission is achieved, but packaging complexity and cost significantly increase
Solution Approach 1:
The patent employs asymmetric chip orientation where only one chip is face-up while the other remains face-down, eliminating the need for face-up/face-down pairing. The edge-to-edge coupling architecture creates an asymmetric packaging structure that reduces complexity compared to symmetric face-to-face configurations.
Solution Approach 2:
Instead of coupling chips face-to-face (conventional approach), the patent inverts the coupling direction by using edge-to-edge coupling with perpendicular substrate orientations. This inversion of the coupling geometry simplifies the packaging structure and reduces the number of required alignment features.
2Adaptability or versatility
If sub-micron waveguide modes are used for edge-to-edge coupling, then waveguide routing flexibility is improved, but mode mismatch losses increase
Solution Approach 1:
The patent introduces an intermediary coupling structure at the waveguide edge that mediates between the confined sub-micron waveguide mode and the free-space optical mode. This intermediary structure enables mode transformation and reduces mode mismatch losses while preserving the routing flexibility of sub-micron waveguides.
Solution Approach 2:
The patent changes the spatial parameters of the optical mode at the waveguide edge by introducing structures that gradually transform the mode size from sub-micron to larger dimensions. This parameter transformation reduces the mode mismatch with free-space optical modes while maintaining the benefits of small-mode waveguides for routing flexibility.
3Loss of energy
If mode converters are used to reduce mode mismatch losses, then optical coupling efficiency is improved, but chip cost and complexity increase
Solution Approach 1:
The patent merges the mode converter functionality directly into the waveguide edge structure itself, eliminating the need for separate, complex mode converter components. By integrating the mode transformation function into the existing waveguide architecture, optical coupling efficiency is improved without proportionally increasing chip complexity.
Solution Approach 2:
The patent designs the waveguide edge structure to serve multiple functions: guiding optical signals, enabling sharp turns, and performing mode transformation. This multi-functional design eliminates the need for dedicated mode converters, reducing chip complexity while maintaining optical coupling efficiency.
4Reliability
If precise alignment is maintained under thermal expansion and vibration, then optical coupling stability is improved, but alignment mechanism complexity increases
Solution Approach 1:
The patent creates an equipotential alignment reference plane using the perpendicular edges of both substrates. This shared reference plane ensures that both substrates align to the same geometric standard, compensating for thermal expansion and vibration effects without requiring complex active alignment mechanisms.
Solution Approach 2:
The patent employs self-aligning features where the perpendicular edges of the substrates automatically define the alignment reference. This passive self-alignment mechanism eliminates the need for complex active alignment systems, maintaining optical coupling stability under environmental disturbances through geometric constraints rather than active control.
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 design facilitates cost-effective and complex-free edge-to-edge optical coupling, maintaining alignment under disturbances, and reduces optical losses by aligning optical components without the need for mode converters in all cases, enabling efficient data communication between chips.
Implementation Method 1
the alignment substrate, which is mechanically coupled to the first substrate and the second optical device, aligns the first edge and the second edge
Implementation Method 2
an optical fiber may be aligned with an on-chip optical waveguide by using a tapered or an inverse tapered optical fiber at the edge of the chip
Implementation Method 3
These modes are facilitated by the strong confinement associated with the large index of refraction difference between the waveguide core and surrounding cladding materials
Implementation Method 4
the strong confinement associated with the large index of refraction difference between the waveguide core and surrounding cladding materials
Data Source
AI summary
An optical module is described. This optical module includes at least two optical devices that communicate with each other using edge-to-edge optical coupling of an optical signal between optical components in the two optical devices. Note that the edge-to-edge optical coupling may occur without mode converters at edges of either of the optical devices. Furthermore, the edge-to-edge optical coupling may be facilitated by an alignment substrate, which is mechanically coupled to the two optical devices. This alignment substrate aligns the edges of the two optical devices so that they are approximately parallel to each other, and aligns the optical components in the two optical devices.