Directional Coupler With Dielectric Core Polymer Cladding

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Solution Overview

Problem

Existing directional couplers lack enhanced tuning capabilities, limiting their effectiveness as wavelength selective filters and multiplexers.

Innovation Solution

A directional coupler with a dielectric core and polymer cladding, arranged in a lateral configuration on a substrate, featuring a grating-assisted coupler design that allows for wavelength tuning by varying the effective refractive index difference between the waveguides, enabling efficient wavelength selection and multiplexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional directional coupler design is used, then the device structure is simple, but the tuning capabilities are limited

Engineering Contradiction:
Improvetuning capabilitiesVSAvoiddevice structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs composite materials by combining a dielectric core waveguide with a polymer cladding material. This composite structure enables enhanced tuning capabilities through the polymer's ability to modify refractive index via temperature or electro-optic effects, while the dielectric core provides structural stability and low loss propagation, thus resolving the contradiction between tuning versatility and device simplicity

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes parameter changes by modifying the effective refractive index of the polymer cladding through temperature variation or electro-optic effects. This allows dynamic tuning of the coupling wavelength without changing the physical structure of the waveguides, thereby achieving enhanced adaptability while maintaining relatively simple device geometry

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the effective refractive index difference between waveguides is increased, then wavelength tuning range is improved, but coupling efficiency may deteriorate

Engineering Contradiction:
Improvewavelength tuning rangeVSAvoidcoupling efficiency
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the polymer cladding's refractive index可调 (tunable) through external stimuli such as temperature or electric field. This dynamic property allows the system to optimize the effective refractive index difference for different operating conditions, enabling broad wavelength tuning while maintaining efficient coupling by adjusting the index difference to appropriate values for each wavelength range

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If a lateral configuration is used, then both waveguides can be used for wavelength tuning, but the device occupies more area

Engineering Contradiction:
Improvewavelength tuning capabilityVSAvoiddevice area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent implements universality by designing a lateral configuration where both the dielectric core waveguide and the polymer cladding waveguide can independently contribute to wavelength tuning. The dielectric core provides one tuning mechanism while the polymer cladding provides another, making both waveguides multi-functional for tuning purposes, thus achieving enhanced versatility despite the increased lateral footprint

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution provides a directional coupler with improved tuning characteristics, allowing for broad wavelength tuning ranges and low-loss operation, suitable for applications like optical add-drop multiplexers and tuneable lasers, with efficient temperature and electro-optic control.

Implementation Method 1

a polymer cladding (111) forming the cladding of both the first and the second optical waveguide

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

the optical waveguides are configured and arranged relative to one another in such a way that an optical wave coupled into one of the two waveguides via its input ending will be transferred to the other waveguide

Methodology Applied
Scientific EffectEvanescent field coupling:

Implementation Method 3

the directional coupler according to the invention can be operated as a wavelength selective optical filter

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentEP2696227B1Directional coupler and optical waveguide
Publication Date: 2019.09.25 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP2696227B1 patent drawingFigure 1~2
  • EP2696227B1 patent drawingFigure 3
  • EP2696227B1 patent drawingFigure 4~5

AI summary

The invention relates to a directional coupler, comprising - a first and a second optical waveguide (110, 120) extending at least partially parallel to one another, wherein - the first and/or the second optical waveguide has a polymer cladding and a core (112) that at least partially comprises or consists of a dielectric material. The invention also relates to an optical waveguide comprising a polymer cladding and a tapered dielectric core.