Optical Grating Coupler Absorber Layer for PIC Testing

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Solution Overview

Problem

Photonic integrated circuits (PICs) face challenges in analyzing optical performance due to light leakage and back-reflections caused by grating couplers during testing, which can destabilize device performance and affect signal integrity.

Innovation Solution

An absorber layer is integrated over the optical grating coupler, separated by a cladding material, to absorb and prevent light reorientation and reduce back-reflections, ensuring accurate optical performance analysis without interfering with the PIC's operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the optical grating coupler is left in place for testing, then optical performance analysis can be performed, but light leakage and back-reflections occur causing device performance degradation

Engineering Contradiction:

Improveoptical performance analysisVSAvoidlight leakage and back-reflections

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful function of the grating coupler by introducing an absorber layer that selectively absorbs the reoriented light, separating the useful coupling function from the harmful light leakage and back-reflection effects

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful back-reflected light into a beneficial absorbed signal by using the absorber layer to capture the reoriented light, transforming the harmful reflection into useful optical power absorption that prevents device degradation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Loss of energy

If the absorber layer is placed directly over the optical grating coupler, then light absorption is maximized, but the grating coupler structure is compromised

Engineering Contradiction:

Improvelight absorption efficiencyVSAvoidgrating coupler functionality

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent introduces a cladding material layer as an intermediary between the absorber layer and the optical grating coupler, allowing the absorber to capture light while the cladding protects the grating coupler structure and maintains its optical coupling functionality

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a nested structure where the absorber layer is positioned within the cladding material, which in turn surrounds the optical grating coupler, creating a protective envelope that allows light absorption without compromising the underlying grating structure

Inventive Principle:

Principle #7Nested doll (Nesting)

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 absorber layer effectively reduces light leakage and back-reflections, allowing for reliable optical performance analysis and stable operation of PICs by absorbing reoriented light, thereby preventing destabilization of optical signals.

Implementation Method 1

an absorber layer over the cladding material, and vertically above the optical grating coupler

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS11536900B2Integrated circuit structure with optical absorber layer over optical grating coupler

Publication Date: 2022.12.27 GLOBALFOUNDRIES US INC

AI summary

Embodiments of the disclosure provide an integrated circuit (IC) structure, including an absorber layer separated from an optical grating coupler by a cladding material. The absorber is positioned to receive light reoriented through the optical grating coupler.