Optical Transmitter-Receiver Shield Electrode Crosstalk Suppression

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Solution Overview

Problem

In optical transmitter-receivers, crosstalk between integrated optical modulators and detectors on the same substrate causes deterioration of reception characteristics due to capacitance between these components and the substrate, leading to signal interference and reduced performance.

Innovation Solution

Incorporating a shield electrode between the optical modulator and detector, connected to the ground wiring line of the electronic circuit chip, which sandwiches the insulating layer with the substrate to intentionally create capacitance and redirect crosstalk signals to the ground, thereby suppressing interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating layer is provided between the optical modulator/detector and the substrate, then electrical isolation is achieved, but capacitance appears between the optical devices and the substrate causing crosstalk

Engineering Contradiction:

Improveelectrical isolationVSAvoidcrosstalk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A shield electrode is introduced as an intermediary component between the optical modulator/detector and the substrate. This shield electrode is connected to ground and creates a capacitive coupling path that intercepts and redirects crosstalk signals to ground, preventing them from reaching the optical devices. The shield electrode acts as a mediator that manages the electrical field distribution and reduces harmful capacitive coupling while maintaining necessary electrical isolation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful capacitance effect into a beneficial shielding mechanism. By intentionally creating a capacitive coupling between the shield electrode and the substrate, the system harnesses the capacitive effect to redirect crosstalk signals to ground. The same physical phenomenon (capacitance) that causes the problem is utilized in a controlled manner to solve the problem, transforming harmful capacitive coupling into a protective shielding mechanism.

Inventive Principle:

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

2Adaptability or versatility

If optical modulator and detector are integrated on the same substrate, then device integration is improved, but crosstalk between components increases

Engineering Contradiction:

ImproveintegrationVSAvoidcrosstalk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The shield electrode serves as a mediating structure between the optical modulator and detector that are integrated on the same substrate. By positioning the shield electrode between these components and connecting it to ground, the invention creates a protective barrier that manages electromagnetic interactions. This intermediary structure enables high-level integration while actively suppressing crosstalk through capacitive coupling to ground.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If shield electrode is added to suppress crosstalk, then reception characteristic is improved, but device complexity increases

Engineering Contradiction:

Improvereception characteristicVSAvoidstructure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shield electrode is implemented as a relatively simple intermediary component that connects to ground through existing ground wiring lines. This approach provides effective crosstalk suppression and improves reception characteristics without requiring complex additional structures. The shield electrode leverages the existing ground infrastructure, minimizing the increase in device complexity while achieving the desired performance improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration effectively suppresses crosstalk signals, improving the reception characteristic by attenuating interference and maintaining signal integrity across a wide frequency range, ensuring better performance in high-capacity communication systems.

Implementation Method 1

the shield electrode is provided sandwiching the insulating layer with the substrate to configure a capacitance

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10830950B2Optical transmitter-receiver

Publication Date: 2020.11.10 FUJITSU LTD

AI summary

An optical transmitter-receiver includes an optical integrated device in which at least an optical modulator and an optical detector are integrated as optical devices over the same substrate and an insulating layer is provided between the optical modulator and the substrate and between the optical detector and the substrate, and an electronic circuit chip that is connected to the optical integrated device and includes an electronic circuit including a ground wiring line. The optical integrated device includes a shield electrode between the optical modulator and the optical detector, and the shield electrode is provided sandwiching the insulating layer with the substrate to configure a capacitance and is connected to the ground wiring line of the electronic circuit chip. By the optical transmitter-receiver, crosstalk through the capacitance between the optical modulator and the substrate, the substrate, and the capacitance between the optical detector and the substrate can be suppressed to suppress deterioration of the reception characteristic.