Non-Periodic Grating Coupler Structure for Stable Optical Coupling

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Solution Overview

Problem

Existing grating coupler structures in integrated optical devices are not entirely satisfactory in terms of coupling efficiency and wavelength shift, particularly due to conventional periodic grating designs that lead to back reflection losses and inefficiencies in light redirection between optical fibers and detectors.

Innovation Solution

The implementation of non-periodic grating bars and intervals in the grating coupler structure, designed to produce a desired intensity profile, is achieved through a method involving high-density plasma chemical vapor deposition (HDP-CVD) to form void-free grating bars and waveguides, enhancing coupling efficiency and reducing wavelength shift issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional periodic grating designs are used, then the structure is simple and easy to manufacture, but coupling efficiency is poor and back reflection losses occur

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidgrating structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by transitioning from conventional periodic grating structures to non-periodic grating bar configurations. The grating bars are positioned at different locations with varying spacing patterns that break the periodic symmetry, enabling control over diffraction patterns to improve coupling efficiency between optical fibers and waveguides while reducing back reflection losses.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent implements local quality by creating non-uniform grating structures where different regions have different grating bar densities and spacing characteristics. This allows localized optimization of coupling performance at specific positions along the waveguide, enabling enhanced light redirection efficiency in critical coupling zones while maintaining simpler structures in other regions.

Inventive Principle:

Principle #3Local quality

2Reliability

If conventional periodic grating designs are used, then manufacturing is straightforward, but wavelength shift occurs and light redirection is inefficient

Engineering Contradiction:

Improvewavelength stabilityVSAvoidgrating fabrication difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the spatial distribution parameters of grating bars from uniform periodic patterns to non-periodic configurations with varying pitch and position. This parameter variation enables wavelength-specific coupling optimization and reduces wavelength shift effects while maintaining compatibility with standard semiconductor manufacturing processes through techniques like selective etching and deposition.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If non-periodic grating bars with varied widths are used, then coupling efficiency improves and back reflection is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvelight redirection efficiencyVSAvoidgrating bar dimension control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the grating structure into discrete grating bar elements with controlled widths and spacing, rather than using continuous periodic structures. This segmentation approach allows independent optimization of each grating bar's dimensions and positions, improving light redirection efficiency while enabling standard fabrication techniques to manage manufacturing precision through sequential processing steps.

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

The non-periodic grating design improves coupling efficiency and reduces back reflection losses, resulting in enhanced light redirection between optical fibers and detectors, thereby improving the overall performance of integrated optical devices.

Implementation Method 1

performing a high-density plasma chemical vapor deposition (HDP-CVD) process to form a filling layer over the first insulating layer and in the grating openings

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS12585065B2Integrated optical devices and methods of forming the same

Publication Date: 2026.03.24 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An integrated optical device includes a substrate, a waveguide structure and a grating structure. The substrate has a waveguide region and a grating region adjacent to each other. The waveguide structure is disposed on the substrate in the waveguide region. The grating structure is disposed on the substrate in the grating region. In some embodiments, the grating structure includes grating bars and grating intervals arranged alternately, and widths of the grating bars of the grating structure are varied.