Optical Waveguide Control Electrode Low Dielectric Layer

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Solution Overview

Problem

Conventional optical waveguide elements face challenges in achieving low voltage driving at high modulation speeds due to difficulties in optical-electrical speed matching and impedance matching, particularly when the distance between RF electrodes is reduced, leading to decreased high-frequency signal propagation speed.

Innovation Solution

The optical waveguide element incorporates a control electrode structure with a low dielectric layer between common and segment electrodes, extending below connection electrodes, and featuring a Mach-Zehnder type optical waveguide configuration, along with a low dielectric substrate and buffer layer, to enhance high-frequency signal propagation and adhesion, facilitating low voltage driving at high speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the distance between RF electrode and ground electrode is reduced to shorten segment electrode spacing, then the size is reduced, but the propagation speed of high frequency signal drops

Engineering Contradiction:
Improvesize of control electrodeVSAvoidpropagation speed of high frequency signal
Core Design Contradiction:
Volume of moving objectVSSpeed

Solution Approach 1:

The invention changes the dielectric constant parameter by introducing a low dielectric layer (with lower dielectric constant than the substrate) between the common electrode and the optical substrate. This parameter change increases the propagation speed of high frequency signals in the RF electrode without requiring increased distance between electrodes, thus resolving the contradiction between miniaturization and signal speed.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If conventional control electrode structure is used, then impedance adjustment flexibility is available, but optical-electrical speed matching becomes difficult at high modulation speeds

Engineering Contradiction:
Improveimpedance adjustment flexibilityVSAvoidoptical-electrical speed matching
Core Design Contradiction:
Adaptability or versatilityVSSpeed

Solution Approach 1:

The invention modifies the electrical parameters of the control electrode by introducing the low dielectric layer, which changes the capacitance and impedance characteristics. This enables both impedance matching and optical-electrical speed matching to be achieved simultaneously at high modulation speeds while maintaining the flexibility of the segment electrode structure.

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

This configuration enables efficient low voltage driving at high modulation speeds by optimizing signal propagation speed and reducing waveguide loss, improving adhesion and reliability, thus achieving effective optical modulation operations.

Implementation Method 1

A low dielectric layer having a relative dielectric constant lower than a relative dielectric constant of the optical substrate is arranged between the common electrode and the optical substrate

Methodology Applied
Scientific EffectDielectric: Dielectric

Implementation Method 2

a control electrode for controlling light waves propagating through the optical waveguide

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

Data Source

PatentEP4394496A1Optical waveguide element, optical modulator, and optical transmission device
Publication Date: 2024.07.03 SUMITOMO OSAKA CEMENT CO LTD
  • EP4394496A1 patent drawingFigure 1
  • EP4394496A1 patent drawingFigure 2
  • EP4394496A1 patent drawingFigure 3

AI summary

An optical waveguide element (3) includes an optical waveguide (31) arranged on a main surface of an optical substrate (30), and a control electrode (42) controlling light waves propagating through the optical waveguide. The control electrode includes a first control electrode (43) and a second control electrode (44) facing each other across the optical waveguide on the main surface of the optical substrate. The first control electrode and the second control electrode each include a common electrode (43a, 44a) extending along the optical waveguide, segment electrodes (43c, 44c) arranged closer to the optical waveguide than the common electrode and divided along an extending direction of the optical waveguide, and connection electrodes (43b, 44b) connecting each of the segment electrodes to the common electrode. A low dielectric layer (45) having a lower relative dielectric constant than the optical substrate is arranged between the common electrode and the optical substrate.