Waveguide-Coupled Photoelectric Transducer With Parabolic Light Coupling

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Solution Overview

Problem

The challenge of efficiently coupling light emitted by a light-emitting diode (LED) source into a waveguide in integrated photonic devices is hindered by incoherent wave emission, refractive index mismatch, and large dimension disparities, leading to significant radiation loss and inefficient light transfer.

Innovation Solution

A cylindrical-parabolic reflective structure is integrated with a photoelectric transducer and waveguide, using transparent materials and reflective surfaces to redirect and concentrate light rays from the LED source into the waveguide, maintaining refractive index continuity and minimizing optical losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If monolithic integration is used to form LED source and waveguide from the same layer, then manufacturing complexity is reduced, but light coupling efficiency deteriorates due to radiation loss in non-adjacent regions

Engineering Contradiction:

Improveintegration complexityVSAvoidlight coupling efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

A reflective structure is introduced as an intermediary element between the LED source and waveguide. This structure reflects and redirects radiation that would otherwise be lost in non-adjacent regions back toward the waveguide, thereby improving light coupling efficiency without increasing manufacturing complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reflective structure converts harmful radiation loss into beneficial light coupling by redirecting previously lost radiation back into the waveguide, transforming energy that would be wasted into useful light transmission

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Volume of moving object

If LED source dimensions are reduced to micrometer scale, then device miniaturization is achieved, but light collection capability deteriorates due to increased divergence

Engineering Contradiction:

ImproveLED source sizeVSAvoidradiation collection efficiency

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The reflective structure employs curved reflective surfaces that are specifically shaped to intercept and redirect divergent radiation from the micrometer-scale LED source. The curvature of the reflective surfaces matches the divergence pattern, effectively collecting and redirecting light that would otherwise be lost

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Stability of the object's composition

If waveguide material with lower refractive index than LED is used, then optical confinement in LED is maintained, but light transfer efficiency deteriorates due to refractive index mismatch

Engineering Contradiction:

Improveoptical confinementVSAvoidlight transfer efficiency

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The reflective structure serves as a mediator that bypasses the refractive index mismatch problem. Instead of relying on direct interface coupling between materials of different refractive indices, the reflective structure redirects light to reach the waveguide, eliminating the need for efficient direct transfer across the refractive index boundary

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances light coupling efficiency by channeling previously lost radiation into the waveguide, allowing for a compact, single-mode optical system with improved guidance and reduced optical losses.

Implementation Method 1

The reflective structure is formed by a parabolic-cylindrical pillar... comprising: a first internal reflection face of parabolic profile disposed on the parabolic lateral surface... a second internal face and a third internal reflection face being flat disposed on the flat lateral surface

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a first internal reflection face of parabolic profile... each parabolic section being defined by a parabola having an optical axis and a focus

Methodology Applied

Scientific EffectOptical focusing: Focusing

Data Source

PatentEP4382977B1Optical system including a waveguide coupled photoelectric transducer and method of manufacturing the same

Publication Date: 2025.11.19 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

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Figure 5A~5E

AI summary

One aspect of the invention relates to an optical system (1) comprising a substrate (10) and, formed on said substrate (10): - a reflective structure (20) comprising a first internal parabolic reflective face (22), a second internal plane reflective face (23), and a third internal plane reflective face (24), - a photoelectric transducer (30) comprising an active region configured to emit light waves or configured to receive light waves and positioned in the reflective structure (20) at a portion of the focal points (Fi), the material (21) of the reflective structure (20) being chosen to be transparent to light waves, - a waveguide (40) arranged such that its longitudinal axis (Xg) is parallel to the optical axes (Xoi) and its proximal end (41) is attached to the reflective structure (20) between the second and third reflective faces (23, 24) and at the region active.