Waveguide Side Illumination at Steep Angles for Increased Coupling

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Solution Overview

Problem

Existing side illumination methods for waveguides, such as optical fibers, result in low coupling efficiency, short propagation lengths, poor sensitivity, and low signal transmission, limiting their applications in sensors and couplers.

Innovation Solution

Increasing the angle of side illumination with respect to the normal of the waveguide surface to steep angles, up to 85 degrees, using configurations like collimated light sources, tapered holes, oblique and upright waveguides, and hybrid configurations to enhance light coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If side illumination is performed at 0 degrees angle (normal to side surface), then the illumination setup is simple, but coupling efficiency is low and propagation length is short

Engineering Contradiction:

Improveillumination setup simplicityVSAvoidcoupling efficiency

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent changes the illumination angle parameter from 0 degrees (normal incidence) to steep angles (up to 85 degrees from normal). This parameter change dramatically increases coupling efficiency by enabling light to enter the waveguide at angles that satisfy total internal reflection conditions, thereby resolving the contradiction between setup simplicity and coupling efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from axial illumination (along the waveguide axis) to lateral illumination (from the side surface). This dimensional change in illumination approach enables steep angle incidence on the side surface, which dramatically improves coupling efficiency while maintaining operational simplicity through direct side illumination

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If side illumination is performed at 0 degrees angle, then the coupling setup is simple, but propagation length is short

Engineering Contradiction:

Improvecoupling setup simplicityVSAvoidpropagation length

Core Design Contradiction:

Ease of operationVSLength of moving object

Solution Approach 1:

By changing the illumination angle parameter to steep angles (up to 85 degrees from normal), the patent enables light to propagate along the waveguide at angles that satisfy total internal reflection conditions. This parameter change extends propagation length from meters to potentially much longer distances, resolving the contradiction between setup simplicity and propagation length

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If side illumination is performed at 0 degrees angle, then the illumination method is simple, but signal transmission is low

Engineering Contradiction:

Improveillumination method simplicityVSAvoidsignal transmission

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The patent changes the illumination angle parameter to steep angles, which increases the amount of light coupled into the waveguide. This parameter change directly increases signal transmission by enabling more photons to enter the waveguide and propagate, resolving the contradiction between illumination simplicity and signal transmission

Inventive Principle:

Principle #35Parameter changes

4Ease of operation

If side illumination is performed at 0 degrees angle, then the coupling configuration is simple, but sensitivity and resolution are poor

Engineering Contradiction:

Improvecoupling configuration simplicityVSAvoidsensitivity and resolution

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

By changing the illumination angle to steep angles (up to 85 degrees from normal), the patent increases coupling efficiency and signal transmission. This parameter change improves sensitivity and resolution by providing stronger optical signals for detection, resolving the contradiction between configuration simplicity and measurement 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

This approach significantly increases coupling efficiency, enabling longer propagation lengths, higher sensitivity, and better resolution in optical fiber sensors, allowing the use of lower intensity light sources and reducing detection system complexity.

Implementation Method 1

side illumination of a waveguide... increasing the angle of side illumination with respect to the normal of the waveguide surface to steep angles, up to 85 degrees... significantly increases coupling efficiency, enabling longer propagation lengths

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

transmission, along a waveguide, of any wave... Electromagnetic waves, such as radio wave, microwave, infrared, visible light, ultraviolet, x-rays and gamma rays

Methodology Applied

Scientific EffectWaveguide propagation: Waveguide (optics)

Data Source

PatentUS20250327963A1Systems and methods of side illumination of waveguides

Publication Date: 2025.10.23 EGALON CLAUDIO OLIVEIRA

AI summary

Systems and methods of side coupling, side illumination or side injection (as opposed to axial coupling, illumination, or injection) of a waveguide are disclosed. More particularly, it relates to increased coupling, by orders of magnitude, and, consequently, increased transmission, along a waveguide, of any wave by side coupling, side illumination, or side injection.