Optical Waveguide Coupler with Tapered Segment for Alignment Tolerance

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Solution Overview

Problem

Conventional optical waveguide couplers with high manufacturing costs and small manufacturing tolerances due to the need for precise fabrication techniques, making mass production challenging.

Innovation Solution

Design of an optical waveguide coupler with a high-refractive-index waveguide having a first and second segment connected along a first direction, where the second segment's thickness gradually decreases, and a low-refractive-index waveguide covering it, with dimensions optimized for alignment and manufacturing using ultraviolet lithography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical waveguide coupler structures are used with precise fabrication techniques, then coupling efficiency is improved, but manufacturing cost increases and manufacturing tolerance decreases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the refractive index parameter by introducing a low-refractive-index waveguide layer with refractive index between the substrate isolation layer and the high-refractive-index waveguide. This parameter change enables effective coupling while allowing broader manufacturing tolerances and reducing fabrication precision requirements.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The low-refractive-index waveguide acts as an intermediary between the optical fiber and the high-refractive-index waveguide. This intermediate structure facilitates gradual mode field transition and coupling, reducing the need for high-precision direct alignment and lowering manufacturing costs.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional optical waveguide coupler structures are used with precise fabrication techniques, then coupling efficiency is improved, but manufacturing tolerance decreases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidmanufacturing tolerance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By changing the refractive index parameter of the waveguide structure, the patent creates a more robust coupling mechanism that is less sensitive to dimensional variations. The low-refractive-index waveguide enables effective coupling even with larger tolerances in width and position.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating a specific low-refractive-index region only where coupling is needed, while maintaining the high-refractive-index waveguide structure elsewhere. This localized modification improves coupling efficiency without requiring high precision across the entire structure.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If the dimension of the second waveguiding segment along the second direction is increased, then alignment tolerance is improved, but the device size increases

Engineering Contradiction:

Improvealignment toleranceVSAvoiddevice size

Core Design Contradiction:

Manufacturing precisionVSArea of moving object

Solution Approach 1:

The patent changes the refractive index parameter to achieve coupling, which reduces the required dimension of the second waveguiding segment along the second direction. This allows maintaining alignment tolerance while minimizing the increase in device size.

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

Improves coupling efficiency and reduces manufacturing costs, enabling mass production by enhancing alignment tolerance and reducing the need for high-precision electron-beam lithography.

Implementation Method 1

The refractive index of the low-refractive-index waveguide is greater than the refractive index of an isolation layer of the substrate and less than the refractive index of the high-refractive-index waveguide, and the low-refractive-index waveguide is configured to transmit a light beam from an optical fiber to the high-refractive-index waveguide

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20250224561A1Optical waveguide coupler and fabrication method therefor

Publication Date: 2025.07.10 NANTONG NANLITAI TECHNOLOGY CO LTD

AI summary

An optical waveguide coupler includes a substrate, a high-refractive-index waveguide, and a low-refractive-index waveguide. The high-refractive-index waveguide is formed on the substrate and includes a first waveguiding segment and a second waveguiding segment that are sequentially connected to each other and extend along a first direction. Along the first direction, the thickness of the second waveguiding segment gradually decreases. The low-refractive-index waveguide is formed on the substrate and covers the high-refractive-index waveguide. The refractive index of the low-refractive-index waveguide is greater than the refractive index of an isolation layer of the substrate and less than the refractive index of the high-refractive-index waveguide, and the low-refractive-index waveguide is configured to transmit a light beam from an optical fiber to the high-refractive-index waveguide. The dimension of the second waveguiding segment along a second direction is greater than a preset value.