Semiconductor-Photonic Assembly Using Double Evanescent Coupling

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Solution Overview

Problem

Achieving optical coupling between silicon photonics (SiPho) waveguides and active semiconductor components with minimal coupling losses and low cost is challenging due to differences in optical mode geometry and alignment tolerance issues, with existing methods being complex, costly, and unreliable.

Innovation Solution

A method involving evanescent coupling between silicon-based passive optical components and active semiconductor components, utilizing double evanescent coupling through intermediate waveguides with specific geometry and alignment, allowing efficient transfer of optical modes despite differing sizes and tolerating misalignments, and using standard manufacturing processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If direct coupling between waveguides is used, then coupling losses can be reduced, but alignment tolerance becomes very low due to mode mismatch

Engineering Contradiction:
Improvecoupling lossesVSAvoidalignment tolerance
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediate waveguide layer between the SiPho waveguide and the active semiconductor component waveguide. This intermediate layer acts as a mediator that gradually transitions the optical mode geometry from one waveguide system to another, reducing mode mismatch and improving alignment tolerance while maintaining low coupling losses.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the waveguide geometry parameters (width, height, thickness) of the intermediate waveguide layer to optimize mode matching. By carefully designing these dimensional parameters, the optical mode profile is gradually transformed, enabling robust coupling despite misalignment.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If optical devices are placed in free space to facilitate coupling, then mode mismatch can be mitigated, but equipment cost and alignment time increase significantly

Engineering Contradiction:
Improvecoupling lossesVSAvoidequipment complexity and alignment time
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

Instead of using free-space optical devices like lenses, the patent employs an integrated intermediate waveguide layer that is part of the semiconductor component structure. This eliminates the need for external optical alignment equipment and reduces alignment time while maintaining effective mode coupling.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical optical alignment systems (lenses, mirrors, positioning stages) with a solid-state waveguide-based evanescent coupling mechanism. This substitution eliminates complex alignment procedures and reduces equipment requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If flip-chip mounting with support points is used, then vertical alignment can be ensured, but horizontal alignment requires very high precision equipment

Engineering Contradiction:
Improvevertical alignmentVSAvoidalignment equipment precision
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The intermediate waveguide layer serves as a mediator that decouples the alignment requirements. It provides a gradual mode transition that is less sensitive to horizontal misalignment, thereby reducing the precision requirements for alignment equipment while maintaining good vertical alignment through the support points.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Manufacturing precision

If evanescent coupling is used, then alignment tolerance can be improved, but coupling losses increase due to mode size differences

Engineering Contradiction:
Improvealignment toleranceVSAvoidcoupling losses
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent optimizes the geometric parameters of the intermediate waveguide layer (thickness, width, material composition) to control the evanescent coupling strength and mode profile. By adjusting these parameters, the system achieves both high alignment tolerance and low coupling losses simultaneously.

Inventive Principle:
Principle #35Parameter changes

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

Enables efficient coupling with reduced losses, improved alignment tolerance, and cost-effective manufacturing by ensuring evanescent coupling even with different optical modes, facilitating integration of active functions on SiPho circuits.

Implementation Method 1

A method involving evanescent coupling between silicon-based passive optical components and active semiconductor components, utilizing double evanescent coupling through intermediate waveguides

Methodology Applied
Scientific EffectEvanescent coupling: Total Internal Reflection

Data Source

PatentEP3994509B1Assembly of an active semiconductor component and of a passive silicon-based optical component
Publication Date: 2025.11.12 ALMAE TECH
  • EP3994509B1 patent drawingFigure 1A~1B
  • EP3994509B1 patent drawingFigure 2A~2B
  • EP3994509B1 patent drawingFigure 2C~2E

AI summary

According to one aspect, one subject of the present description is an assembly (400) comprising a carrier, an active semiconductor component (200) and a passive silicon-based optical component (300), said components being arranged on the carrier. The active semiconductor component comprises at least one first waveguide (212) configured to guide, through a first section (1) of the assembly, at least one first optical mode, and at least one second waveguide (222), said first and second waveguides being configured to allow evanescent coupling therebetween in a second section (2) of the assembly. A first surface (321) of the passive component (300) makes contact with a first surface (231) of the active component so as to allow transfer, via evanescent coupling, of an optical mode propagating through the second waveguide (222) of the active component into a waveguide (312) of the passive component.