Rib-Type Optical Waveguide Curved Slope Surface

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Solution Overview

Problem

Optical waveguide devices face issues with peeling or cracking of dielectric layers, particularly in micro-optical waveguides with small mode field diameters and tight bending radii, leading to increased optical loss and mechanical instability.

Innovation Solution

The optical waveguide device features a rib-type optical waveguide with a curved slope surface and a dielectric layer that functions as both a core and clad, with a refractive index lower than the waveguide, and includes a spot size converter to manage mode diameter and reduce insertion loss, while the curved surface enhances contact area and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the width and height of the optical waveguide are decreased to reduce size and increase light confinement, then the bending radius is decreased and device size is reduced, but surface roughness significantly increases optical loss

Engineering Contradiction:

Improvedevice sizeVSAvoidoptical loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The side surface of the rib-type optical waveguide is formed with a curved surface (slope shape) instead of a vertical flat surface. This curvature reduces surface roughness effects and decreases optical loss while maintaining the reduced waveguide dimensions for compact device size.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

A dielectric layer with different refractive index is formed on the optical waveguide to create a composite structure. This composite design allows the waveguide to maintain small dimensions for light confinement while the dielectric layer compensates for surface roughness-induced optical loss.

Inventive Principle:

Principle #40Composite materials

2Loss of energy

If a dielectric layer is added to cover the optical waveguide to reduce optical loss from surface roughness, then optical loss is decreased, but the device complexity and manufacturing steps increase

Engineering Contradiction:

Improveoptical lossVSAvoidstructure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The dielectric layer formation is integrated with the existing optical waveguide fabrication process, combining multiple functions into a unified structure that reduces overall device complexity despite adding the dielectric layer.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The dielectric layer serves multiple functions: reducing optical loss from surface roughness, providing mechanical protection, and potentially serving as part of the optical mode structure. This multi-functionality justifies the added structural element.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Volume of moving object

If the mode field diameter is reduced to increase light confinement and decrease bending radius, then device size is reduced, but insertion loss when joining to optical fiber increases

Engineering Contradiction:

Improvedevice sizeVSAvoidinsertion loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The mode field diameter of the optical waveguide is carefully optimized to balance light confinement (for small device size) and compatibility with optical fiber coupling (to minimize insertion loss). Specific parameter ranges are established to achieve this balance.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If a rib-type optical waveguide is formed with vertical side surfaces, then manufacturing is simplified, but surface roughness from etching increases optical loss

Engineering Contradiction:

Improvefabrication simplicityVSAvoidoptical loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 suppresses peeling and cracking of the dielectric layer, reduces optical loss, and maintains mechanical integrity, enabling smaller, more efficient optical waveguide devices for high-frequency communication.

Implementation Method 1

As the width or a height of the optical waveguide is decreased, roughness of a surface of the optical waveguide significantly affects an optical loss of a light wave propagating through the optical waveguide

Methodology Applied

Scientific EffectSurface roughness reduction:

Implementation Method 2

optical waveguide device including an optical waveguide formed on a substrate and a dielectric layer covering the optical waveguide

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

at least a part of a side surface of the rib type optical waveguide along a longitudinal direction has a slope shape formed with a curved surface

Methodology Applied

Scientific EffectSurface area increase:

Implementation Method 4

a dielectric layer covering the optical waveguide

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20240231134A1Optical waveguide element, and optical modulation device and optical transmission apparatus which use same

Publication Date: 2024.07.11 SUMITOMO OSAKA CEMENT CO LTD

AI summary

An object is to provide an optical waveguide device including a dielectric layer covering an optical waveguide, in which occurrence of a problem such as peeling or cracking of the dielectric layer is suppressed. An optical waveguide device of the present invention includes an optical waveguide 2 formed on a substrate 1, and a dielectric layer IL covering the optical waveguide, in which the optical waveguide 2 is a rib type optical waveguide, and at least a part of a side surface of the rib type optical waveguide along a longitudinal direction has a slope shape formed with a curved surface (R6).