Tapered Waveguide Coupled to V-Shaped Branch for High-Power PIC

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Solution Overview

Problem

Photonic integrated circuit (PIC) structures face transmission failures when high power optical signals are transmitted due to power-induced defects, such as melting and damage, at the interface between waveguides with different refractive index profiles.

Innovation Solution

The PIC structure incorporates a first waveguide with a tapered end portion and a second waveguide with two branch waveguides that form a V or U shape, allowing for multiple mode matching locations and reducing light signal power density to prevent power-induced damage, thereby facilitating robust high-power optical signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single waveguide interface is used for high power optical signal transmission, then the structure is simple, but power-induced defects occur due to excessive power density at the interface

Engineering Contradiction:

Improvewaveguide structureVSAvoidtransmission reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The second waveguide is segmented into two branch waveguides that form a V-shape configuration. This segmentation divides the optical signal into two separate paths, reducing the power density at each interface point and preventing power-induced defects while maintaining structural feasibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The waveguide interface is extended from a single-point contact to a distributed interface along the V-shaped branch waveguides. By introducing spatial distribution in the lateral dimension, the optical power is spread across multiple locations, reducing peak power density and preventing damage

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If waveguides with different refractive index profiles are used, then the waveguide can accommodate different optical modes, but power-induced melting and damage occur at the interface

Engineering Contradiction:

Improveoptical mode compatibilityVSAvoidpower-induced damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The interface between waveguides with different refractive index profiles is segmented into multiple contact points along the V-shaped branch waveguides. This segmentation distributes the optical power across several locations, preventing excessive power density that would cause melting or damage at any single interface point

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The V-shaped branch waveguide configuration creates localized mode matching regions at specific points along the interface, allowing different refractive index profiles to be joined while maintaining optimal optical coupling at each local interface point without excessive power concentration

Inventive Principle:

Principle #3Local quality

3Reliability

If a tapered end portion is used for mode matching, then optical signal transmission is improved, but the interface remains vulnerable to power-induced defects

Engineering Contradiction:

Improveoptical signal transmissionVSAvoidpower-induced defects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The tapered end portion is paired with V-shaped branch waveguides that segment the interface into multiple locations. This segmentation distributes the optical power across several interface points along the taper, maintaining good mode matching while preventing excessive power density that would cause damage

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 effectively prevents power-induced defects and ensures reliable transmission of high-power optical signals by creating multiple signal paths and reducing power density at any single interface point.

Implementation Method 1

mode matching occurs (i.e., where the propagation constant of optical mode inside the two waveguides becomes the same)... where the cross-sectional areas of the two end portions of the two waveguides are approximately the same... where the two end portions may have different cross-sectional areas but the same propagation constant which is determined by the respective combinations of refractive index and cross-sectional area

Methodology Applied

Scientific EffectMode matching: Refraction

Data Source

PatentUS11747560B2Photonic integrated circuit structure with a tapered end portion of one waveguide adjacent to a v-shaped end portion of a different waveguide

Publication Date: 2023.09.05 GLOBALFOUNDRIES US INC

AI summary

Disclosed is a photonic integrated circuit (PIC) structure including: a first waveguide with a first main body and a first end portion, which is tapered; and a second waveguide with a second main body and a second end portion, which has two branch waveguides that are positioned adjacent to opposing sides, respectively, of the first end portion of the first waveguide and that branch out from the second main body, thereby forming a V, U or similar shape. The arrangement of the two branch waveguides of the second end portion of the second waveguide relative to the tapered first end portion of the first waveguide allows for mode matching conditions to be met at multiple locations at the interface between the waveguides, thereby creating multiple signal paths between the waveguides and effectively reducing the light signal power density along any one path to prevent or at least minimize any power-induced damage.