Edge Couplers with Dual Ring Resonators for Low Loss Mode Conversion

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Solution Overview

Problem

Current edge couplers in photonics chips face challenges in efficiently confining and transferring light due to the narrow tip of the inverse taper, leading to significant electromagnetic field distribution and mode size variations, which affect mode conversion and insertion loss.

Innovation Solution

Incorporating a structure with a longitudinal axis and two ring resonators, where the ring resonators are laterally and longitudinally offset from the edge coupler to minimize insertion loss and support weak optical coupling, allowing for effective mode transformation and polarization-sensitive light coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the inverse taper tip cross-section area is reduced to enable mode transformation, then mode conversion capability is improved, but light confinement ability deteriorates

Engineering Contradiction:

Improvemode conversion capabilityVSAvoidinsertion loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The waveguide structure is divided into multiple segments: the inverse taper section for mode transformation, and the ring resonator sections for light confinement and wavelength filtering. This segmentation allows each section to optimize its function independently, resolving the contradiction between mode conversion and light confinement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ring resonators serve as intermediary structures between the inverse taper and the output waveguide. They capture and confine the transformed modes, preventing energy loss while maintaining the mode conversion capability of the inverse taper.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the inverse taper width is increased to improve light confinement, then electromagnetic field confinement is improved, but mode transformation efficiency deteriorates

Engineering Contradiction:

Improveelectromagnetic field confinementVSAvoidmode transformation efficiency

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The structure separates the mode transformation function (inverse taper with narrow tip) from the light confinement function (ring resonators with wider cross-section). This allows the inverse taper to be optimized for mode transformation while the ring resonators provide strong light confinement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ring resonators are positioned to overlap with the inverse taper region, creating a nested configuration where the resonators provide confinement enhancement in the regions where the taper is narrowest, without interfering with the mode transformation process.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If ring resonators are added to enhance light confinement and reduce insertion loss, then optical performance is improved, but device complexity increases

Engineering Contradiction:

Improveoptical performanceVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ring resonators are integrated with the waveguide core in a unified structure, sharing common fabrication processes and material layers. This merging approach reduces the overall device complexity compared to adding separate confinement structures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ring resonators serve multiple functions simultaneously: they provide light confinement, enable wavelength-selective filtering, and assist in mode transformation. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 proposed structure enhances light confinement and reduces insertion loss, enabling efficient mode transformation and polarization mode detection while maintaining minimal impact on the optical path, thus improving the overall performance of the edge coupler.

Implementation Method 1

the ring resonators are laterally and longitudinally offset from the edge coupler to minimize insertion loss and support weak optical coupling

Methodology Applied

Scientific EffectOptical coupling: Waveguide (optics)

Implementation Method 2

first ring resonator and a second ring resonator... enabling efficient mode transformation and polarization mode detection

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11880065B2Edge couplers integrated with dual ring resonators

Publication Date: 2024.01.23 GLOBALFOUNDRIES US INC

AI summary

Structures including an edge coupler and methods of fabricating a structure including an edge coupler. The structure includes an edge coupler having a longitudinal axis, a first ring resonator, and a second ring resonator. The first ring resonator has a first center point that is spaced from the longitudinal axis of the edge coupler by a first perpendicular distance. The second ring resonator has a second center point that is spaced from the longitudinal axis of the edge coupler by a second perpendicular distance.