Vertical Interferometric Attenuator for Dense Photonic Integration

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Solution Overview

Problem

Traditional photonic components for modifying optical properties in dense waveguide networks, such as attenuators, have a large surface area that is incompatible with the high guide density required for applications like 3D imaging and retinal projection, making integration difficult due to lateral electrical access and width issues.

Innovation Solution

A photonic circuit with a Mach-Zehnder interferometer arranged in two distinct parallel layers, utilizing a thermo-optical phase shifter to introduce a phase difference between optical signals in the waveguides, and evanescent optical coupling for signal transfer, reducing the footprint and enabling easier integration into dense networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If traditional interferometric attenuators are used, then optical signal attenuation can be achieved, but the device occupies a large surface area that is incompatible with dense waveguide networks

Engineering Contradiction:

Improveoptical signal attenuationVSAvoiddevice surface area

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The patent transitions from a planar interferometric structure to a three-dimensional stacked configuration where waveguides are arranged in multiple vertical layers. The coupling sections enable optical energy transfer between layers through evanescent coupling, effectively utilizing the vertical dimension to reduce the lateral footprint of the attenuator while maintaining its attenuation functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Loss of energy

If traditional interferometric attenuators are used, then optical signal attenuation can be achieved, but the device width is much greater than that of a single waveguide

Engineering Contradiction:

Improveoptical signal attenuationVSAvoiddevice width

Core Design Contradiction:

Loss of energyVSLength of stationary object

Solution Approach 1:

The patent reconfigures the interferometer from a lateral arrangement to a vertical stacking arrangement. The first and second waveguides are positioned in different vertical layers and coupled through evanescent coupling in dedicated coupling sections, thereby reducing the device width to be comparable to single waveguide dimensions while preserving the interferometric attenuation mechanism.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Loss of energy

If traditional interferometric attenuators are used, then optical signal attenuation can be achieved, but lateral electrical access is required which complicates integration into dense networks

Engineering Contradiction:

Improveoptical signal attenuationVSAvoidelectrical access complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent replaces the traditional lateral electrical control mechanism with a vertical evanescent coupling mechanism. The attenuator functionality is achieved through optical field interaction between vertically stacked waveguides in coupling sections, eliminating the need for lateral electrical connections and simplifying integration into dense waveguide networks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 allows for variable attenuation of optical signals with a reduced area footprint, maintaining waveguide density and enabling efficient integration into dense networks while controlling phase difference and intensity manipulation.

Implementation Method 1

The phase shifter is a thermo-optical phase shifter arranged to act preferentially on one of the first and second waveguides by preferentially heating one of the first and second waveguides

Methodology Applied

Scientific EffectThermo-optical effect:

Implementation Method 2

a first transfer section capable of separating, by evanescent optical coupling, an input optical signal circulating on the input waveguide between the first optical signal circulating on the first waveguide and the second optical signal circulating on the second waveguide

Methodology Applied

Scientific EffectEvanescent optical coupling:

Implementation Method 3

a second transfer section capable of combining, by evanescent optical coupling, the first optical signal circulating on the first waveguide and the second optical signal circulating on the second waveguide into an output optical signal circulating on the output waveguide

Methodology Applied

Scientific EffectEvanescent optical coupling:

Data Source

PatentUS11409181B2Attenuator photonic circuit with vertical interferometric structure

Publication Date: 2022.08.09 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

The invention relates to a photonic circuit for attenuating the amplitude of an optical signal, comprising a Mach-Zehnder interferometer for coupling an input waveguide (14) and an output waveguide (15), said interferometer comprising a modulation section (SM1) which includes a first waveguide (11), a second waveguide (12) and a phase shifter (13) configured to introduce a phase difference between a first optical signal circulating on the first waveguide and a second optical signal circulating on the second waveguide.The first and second waveguides are arranged in two distinct parallel layers and the phase shifter is a thermo-optical phase shifter arranged to preferentially act on one of the first and second waveguides.