Resonant Periodic Structures for Tunable Optical Sensing

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Solution Overview

Problem

Existing optical sensors and filters based on guided mode resonant structures require a waveguide layer, which introduces sensitivity issues due to refractive index variations and manufacturing tolerances, and often rely on high refractive index materials that limit the sensitivity and tunability of the devices.

Innovation Solution

A periodic structure without a waveguide layer, featuring a thick grating with high Fresnel reflections and a stratified periodic stack, where the spaces between grating lines are empty or filled with a material matching the substrate's refractive index, allowing for increased sensitivity and tunability by using plasmonic nanoparticles and a functionalization layer for biological or chemical entity detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a waveguide layer is used in guided mode resonant structures, then the device can achieve optical filtering and sensing functions, but the refractive index variations and manufacturing tolerances reduce the sensitivity and reliability

Engineering Contradiction:

ImprovesensitivityVSAvoidrefractive index variation tolerance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent removes the waveguide layer from the guided mode resonant structure, extracting the problematic component that causes sensitivity to refractive index variations. The grating layer is made directly on the substrate without requiring a separate waveguide layer, thereby eliminating the manufacturing precision issues associated with the waveguide layer's refractive index control.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates local quality differences by having the grating layer directly on the substrate in contact with the analyte, while other regions maintain their original structure. This local modification allows the sensing region to have direct interaction with the analyte without being constrained by waveguide layer properties.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If high refractive index materials are used in the waveguide layer, then the optical confinement is improved, but the tunability and sensitivity of the device are limited

Engineering Contradiction:

Improveoptical confinementVSAvoidtunability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent changes the structural parameters of the device by removing the waveguide layer and allowing the grating layer to be in direct contact with the analyte. This parameter change enables the effective refractive index to be dynamically adjusted by the analyte's refractive index, thereby improving tunability while maintaining optical confinement through the grating structure itself.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a waveguide layer is required for GMR structures, then the manufacturing process becomes more complex, but the device can still achieve sensing functionality

Engineering Contradiction:

Improvesensing functionalityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the waveguide layer from the device structure, simplifying the overall architecture. The grating layer is deposited directly on the substrate, reducing the number of layers and interfaces that need to be controlled during manufacturing, thereby reducing device complexity while maintaining sensing functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of the waveguide layer and the grating layer into a single configuration where the grating layer serves both as the resonant structure and as the element in direct contact with the analyte. This merging eliminates the need for a separate waveguide layer, simplifying the manufacturing process.

Inventive Principle:

Principle #5Merging (Combining)

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 enhances the sensitivity and tunability of the optical device, enabling effective refractive index determination and detection of biological or chemical entities with improved accuracy and reliability, while reducing manufacturing complexities.

Implementation Method 1

A good example of such structure is the metallic grating structure which can excite surface plasmon resonances sensitive to the refractive index of the analyte material adjacent to the surface

Methodology Applied

Scientific EffectSurface plasmon resonance: Resonance

Implementation Method 2

the Fresnel reflections between the interfaces of the thick grating lines and the adjacent materials are higher than 10%

Methodology Applied

Scientific EffectFresnel reflection: Reflection

Data Source

PatentUS10801956B2Resonant periodic structures and methods of using them as filters and sensors

Publication Date: 2020.10.13 PHOTONICSYS

AI summary

The invention relates to the field of surface waves based optical devices particularly tuneable optical filter, optical biosensors and spatial light modulators. An optical sensor and tuneable filter is disclosed based on high contrast periodic structures deposited on a substrate and using a compact reading method for low detection limit using a one dimensionally diverging quasi-monochromatic beam and a camera.