Adiabatic Waveguide Modulator Layout for Low Optical Loss

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Solution Overview

Problem

Conventional integrated modulators suffer from high loss due to absorption in active sections, and existing lithium niobate modulators do not utilize high confinement optical modes effectively.

Innovation Solution

A hybrid optical modulator design incorporating both narrow single mode and wider multimode waveguides, with adiabatic tapers to transition between modes, reducing optical loss by exciting only the fundamental mode in the wider waveguides.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional integrated modulators use active sections with electrodes for modulation, then modulation function is achieved, but optical loss increases due to absorption

Engineering Contradiction:

Improvemodulation functionVSAvoidoptical loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The waveguide is divided into distinct single-mode and multi-mode sections with adiabatic tapers connecting them. This segmentation allows the light to be confined to a small core in single-mode sections (enabling efficient modulation) while propagating in a larger effective area in multi-mode sections (reducing absorption losses), thereby resolving the contradiction between achieving modulation function and minimizing optical loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the waveguide are designed with different modal characteristics - single-mode sections provide high confinement for efficient electrode interaction, while multi-mode sections provide low loss propagation. This local differentiation of waveguide properties allows each section to optimize for its specific function, resolving the contradiction between modulation efficiency and loss reduction.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If narrow single mode waveguides are used for high confinement, then modulation efficiency is improved, but optical propagation loss increases

Engineering Contradiction:

Improveconfinement efficiencyVSAvoidpropagation loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The waveguide path is segmented into single-mode sections for confinement and multi-mode sections for low-loss propagation. Adiabatic tapers connect these segments, enabling the system to exploit the advantages of both waveguide types - high confinement where needed and low loss where propagation occurs, thereby resolving the contradiction between confinement efficiency and propagation loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Adiabatic tapers serve as intermediary transition regions between single-mode and multi-mode waveguide sections. These tapered sections enable smooth mode transformation with minimal scattering loss, allowing the system to switch between high-confinement and low-loss propagation regimes, thus resolving the contradiction between confinement and propagation loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of energy

If wider multimode waveguides are used for low loss, then propagation loss is reduced, but mode confinement decreases

Engineering Contradiction:

Improvepropagation lossVSAvoidmode confinement

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The waveguide is segmented into multi-mode sections for low-loss propagation and single-mode sections for high confinement. By strategically placing single-mode sections at locations requiring strong electrode interaction, the system maintains low overall propagation loss while ensuring sufficient confinement where modulation occurs, resolving the contradiction between propagation loss and mode confinement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the waveguide are assigned different modal qualities - multi-mode sections provide low-loss propagation with relaxed confinement requirements, while single-mode sections provide high confinement for efficient modulation. This local optimization of waveguide properties resolves the contradiction between propagation loss and confinement by applying the appropriate mode regime in the appropriate location.

Inventive Principle:

Principle #3Local quality

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 hybrid modulator design significantly reduces optical propagation loss by minimizing scattering and absorption, while maintaining high confinement and efficient mode conversion.

Implementation Method 1

adiabatic tapers to transition between modes, reducing optical loss by exciting only the fundamental mode in the wider waveguides

Methodology Applied

Scientific EffectAdiabatic mode transformation: Adiabatic Heating

Implementation Method 2

existing lithium niobate modulators based on electro-optic effect

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS20260036836A1Low-loss waveguiding structures, in particular modulators

Publication Date: 2026.02.05 HYPERLIGHT CORP

AI summary

An optical modulator that uses adiabatic tapers to change the width of the waveguides between multimode waveguides and single mode waveguides on a low-loss, e.g. thin-film lithium niobate, electro-optic platform. The architecture enables the utilization of the fundamental mode of multimode wide optical waveguides that have lower optical propagation loss without sacrificing the benefit of the signal integrity and ease of control of single mode operation.