Evanescent Coupled Waveguide Demultiplexer for Infrared Imaging

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Solution Overview

Problem

Existing wavelength demultiplexing technologies face challenges in efficiently separating spectral contributions of an incident light beam, particularly in infrared wavelengths, and integrating these devices into compact lens-less imaging systems without complex alignment requirements.

Innovation Solution

A wavelength demultiplexing device comprising a linear waveguide and a planar waveguide optically coupled by evanescent coupling, with a diffraction grating assembly for extracting light at different wavelengths, allowing for spatial separation and distribution of spectral contributions within a compact and thin form factor, suitable for integration in infrared imaging systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional wavelength demultiplexing technologies (AWG, PCG, resonant ring grating) are used, then spectral separation is achieved, but device complexity and alignment requirements increase

Engineering Contradiction:

Improvespectral separation precisionVSAvoiddevice structural complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The device segments the wavelength demultiplexing function into two distinct waveguide components: a linear waveguide for spectral dispersion and a planar waveguide for spatial separation. This segmentation allows each component to perform a specific function with simpler structure, avoiding the complexity of integrated solutions like AWG or resonant ring gratings while maintaining effective spectral separation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The planar waveguide acts as an intermediary between the linear waveguide and the output plane. It receives the spectrally dispersed light from the linear waveguide via evanescent coupling and redistributes it spatially, serving as a mediator that simplifies the overall system architecture while achieving both spectral and spatial separation functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If conventional demultiplexing devices are designed for compact integration, then device size is reduced, but alignment precision requirements increase

Engineering Contradiction:

Improvedevice volumeVSAvoidalignment precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The linear and planar waveguides are merged into a single integrated structure fabricated on the same substrate using the same material layer. This merging eliminates the need for separate alignment procedures between distinct components, as the evanescent coupling interface is formed during a single fabrication process, thereby reducing alignment precision requirements while maintaining compact device volume.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The waveguides are designed to be self-aligning through their geometric configuration and optical mode profiles. The evanescent coupling between the linear and planar waveguides occurs automatically at their interface without requiring external alignment mechanisms, allowing the device to self-adjust during operation and reducing manufacturing precision constraints.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If evanescent coupling is used for optical coupling between waveguides, then light transfer efficiency is improved, but coupling distance control precision must be increased

Engineering Contradiction:

Improvelight transfer efficiencyVSAvoidcoupling distance precision

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The design optimizes the coupling distance parameter by adjusting the vertical position and thickness of the planar waveguide relative to the linear waveguide. By carefully controlling these geometric parameters during fabrication, the evanescent coupling efficiency is maximized while tolerating reasonable variations in manufacturing precision, thus achieving high light transfer efficiency without requiring extreme coupling distance precision.

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

The device effectively separates and distributes infrared spectral contributions, enabling efficient wavelength demultiplexing with reduced thickness and alignment constraints, suitable for compact imaging systems, and allows for homogeneous illumination of large surfaces.

Implementation Method 1

configured so as to be optically coupled with one another by evanescent coupling along a coupling line, when in use

Methodology Applied

Scientific EffectEvanescent coupling:

Implementation Method 2

an extraction assembly, located in the planar waveguide, and consisting of a plurality of diffraction grating each configured to extract light out of the planar waveguide

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS11448826B2Wavelength demultiplexing device in particular for out-of-plane demultiplexing

Publication Date: 2022.09.20 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A wavelength demultiplexing device configured so as to spatially distributing the spectral contributions of an incident light beam, when in use, and which includes a linear waveguide and a planar waveguide, formed in a coplanar way and adapted to be optically coupled with one another along a coupling line, by evanescent coupling. Such a device may further include diffraction gratings located in the planar waveguide, to extract light out of the latter.