Integrated Optical-Waveguide Depolarizer for Polarization Uniformity

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Solution Overview

Problem

Existing depolarizers using polarization maintaining optical fibers or optical waveguides in planar lightwave circuits face issues with polarization maintenance and compactness, leading to inefficiencies and deviations in polarization states.

Innovation Solution

A depolarizer design integrating a splitter, delay applying portion, polarization converter, and coupler on a single optical waveguide substrate, utilizing heaters for adjustable branching and multiplexing ratios, and orthogonal polarization conversion to achieve uniform depolarization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If polarization maintaining optical fibers or optical waveguides are used in existing depolarizers, then polarization state stability is improved, but device complexity and size increase

Engineering Contradiction:

Improvepolarization state stabilityVSAvoiddevice complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent integrates the splitter, delay applying portion, polarization converter, and coupler onto a single optical waveguide substrate. This merging of previously separate components into one integrated device reduces overall system complexity while maintaining the polarization stability function through the coordinated operation of these integrated elements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The optical waveguide substrate serves multiple functions simultaneously: it acts as the substrate for integration, provides the waveguide paths for light propagation, enables the splitter function, supports the delay applying portion, and facilitates the coupler operation. This multi-functionality reduces the need for separate polarization-maintaining components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If polarization maintaining optical fibers or optical waveguides are used in existing depolarizers, then polarization state stability is improved, but the device size increases

Engineering Contradiction:

Improvepolarization state stabilityVSAvoiddevice size

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Volume of moving object

If integrated design is used to reduce device size, then compactness is improved, but polarization uniformity may deteriorate

Engineering Contradiction:

Improvedevice sizeVSAvoidpolarization uniformity

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by implementing specific design features in different regions of the integrated device: the delay applying portion uses curved optical waveguides with specific curvature radii to control polarization, the polarization converter is positioned at specific locations, and the splitter and coupler have optimized geometries. This localized optimization ensures polarization uniformity is maintained despite the integrated compact design.

Inventive Principle:

Principle #3Local quality

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 integrated design enhances polarization uniformity, reduces optical loss, and allows for compact deployment, supporting multiple light sources and improved monitoring capabilities.

Implementation Method 1

a delay applying portion including optical waveguides including a plurality of curved optical wavelengths, the delay applying portion being configured to apply a differential group delay with respect to the second light to the first light to output the first light having the differential group delay

Methodology Applied

Scientific EffectDifferential group delay:

Implementation Method 2

a polarization converter configured to convert a polarization state of either the first light or the second light into an orthogonal polarization state to output a post-conversion polarization light

Methodology Applied

Scientific EffectPolarization conversion: Polarisation

Data Source

PatentUS20250284063A1Depolarizer, depolarizer adjustment method, and depolarizer manufacturing method

Publication Date: 2025.09.11 FURUKAWA ELECTRIC CO LTD

AI summary

A depolarizer includes: a splitter configured to branch an input light into at least a first light and a second light; a delay applying portion configured to apply a differential group delay with respect to the second light to the first light; a polarization converter configured to convert a polarization state of either the first light or the second light into an orthogonal polarization state; a coupler configured to either multiplex the first light, which has passed through the delay applying portion and the polarization converter, and the second light, or multiplex the first light which has passed through the delay applying portion and the second light which has passed through the polarization converter; and a connecting optical waveguide configured to optically connect the splitter and the coupler.