Optical Waveguide Control Electrode Segmentation

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Solution Overview

Problem

Optical waveguide elements face challenges with conductor loss and manufacturing difficulties due to oxidation of non-gold electrodes, particularly in high-frequency applications, where gold usage is undesirable for cost and ease of connection.

Innovation Solution

A control electrode made of materials like silver or copper, with gold limited to wire bonding areas to ensure stable connections and minimize conductor loss, while avoiding gold on signal and ground electrode surfaces to maintain uniform resistance and reduce propagation loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If materials other than gold (such as silver or copper) are used for the control electrode to reduce cost and improve conductivity, then conductor loss is reduced and high-frequency characteristics are improved, but the electrode surface oxidizes making wire bonding difficult

Engineering Contradiction:
Improveconductor lossVSAvoidease of wire bonding
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The control electrode is divided into two distinct parts: a signal electrode portion made of low-conductivity material (silver or copper) for minimizing conductor loss, and a separate gold portion provided only at wire bonding portions for enabling reliable electrical connection. This segmentation allows each part to optimize its function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Gold is applied locally only at the wire bonding portions rather than uniformly across the entire electrode surface. This localized application ensures that wire bonding areas have the necessary connectivity properties while the signal transmission areas maintain optimal electrical characteristics for high-frequency operation.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If gold is formed as an anti-oxidation film on the entire surface of the electrode to prevent oxidation, then ease of wire bonding is improved, but high-frequency characteristics deteriorate and cost increases

Engineering Contradiction:
Improveease of wire bondingVSAvoidconductor loss
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The electrode structure is segmented into a signal electrode portion and a separate gold portion, with gold restricted only to wire bonding areas. This prevents gold from covering the signal transmission path, thereby avoiding the deterioration of high-frequency characteristics while still providing necessary bonding surfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Gold is applied with local quality - present only where needed for wire bonding and absent from signal transmission areas. This selective placement maintains uniform resistance distribution on the electrode surface, preventing signal distortion and minimizing conductor loss in high-frequency applications.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If gold film is partially disposed on the signal electrode to enable wire bonding, then ease of wire bonding is improved, but electric resistance becomes uneven and propagation loss increases

Engineering Contradiction:
Improveease of wire bondingVSAvoidpropagation loss
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The control electrode is segmented into a signal electrode portion and a gold portion, with the gold portion positioned only at wire bonding portions and not on the signal electrode surface. This segmentation ensures uniform electric resistance distribution across the signal transmission area, preventing signal distortion and minimizing propagation loss.

Inventive Principle:
Principle #1Segmentation

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 enables effective wire bonding, reduces gold usage and cost, and minimizes conductor loss by maintaining uniform resistance and reducing propagation loss of high-frequency signals.

Implementation Method 1

from the viewpoint of light modulation operation, it is desirable that conductivity is higher and a conductor loss is smaller

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

even in a case where an insulator covers a surface of a metal film, it is known that a skin effect is exhibited by using a portion where a signal current has a low resistance (non-oxidized portion)

Methodology Applied
Scientific EffectSkin effect: Skin Effect

Implementation Method 3

an optical waveguide element including a substrate having an electro-optic effect, an optical waveguide formed on the substrate, and a control electrode provided on the substrate and controlling a light wave propagating through the optical waveguide

Methodology Applied
Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 4

an optical waveguide formed on the substrate, and a control electrode provided on the substrate and controlling a light wave propagating through the optical waveguide

Methodology Applied
Scientific EffectOptical waveguide effect: Waveguide (optics)

Data Source

PatentEP3779576B1Optical waveguide element
Publication Date: 2024.03.20 SUMITOMO OSAKA CEMENT CO LTD
  • EP3779576B1 patent drawingFigure 1~2
  • EP3779576B1 patent drawingFigure 3~4

AI summary

Provided is an optical waveguide element capable of connection such as wire bonding, suppressing usage of gold, and suppressing deterioration of a conductor loss. An optical waveguide element includes a substrate 1 having an electro-optic effect, an optical waveguide 2 formed on the substrate, and a control electrode (30, 31) provided on the substrate and controlling a light wave propagating through the optical waveguide. The control electrode is made of a material other than gold, and the gold is disposed on at least a wire bonding portion 4 of the control electrode.