Waggled Waveguide Transition for Low-Loss Optical Splitting

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Solution Overview

Problem

Planar Lightwave Circuits (PLCs) face significant optical loss issues due to imperfections in Y-Branch waveguides, leading to reduced signal integrity and efficiency, especially when cascaded, as existing designs struggle to minimize excess loss and maintain optimal splitting performance.

Innovation Solution

The introduction of a 'waggled' waveguide transition section in Y-Branch splitters, which alternates between gapped and ungapped segments, helps to reduce optical loss by maintaining a constant total core cross-section and optimizing the refractive delay, allowing for smoother splitting and improved coupling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional Y-Branch waveguide designs are used, then the structure is simple and easy to manufacture, but optical loss is high and signal integrity is reduced

Engineering Contradiction:
Improveoptical lossVSAvoidwaveguide transition structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The waveguide transition section is segmented into alternating gapped and ungapped segments along the optical path. This segmentation creates a periodic structure that controls optical mode coupling and reduces scattering loss at the branch point, thereby reducing overall optical loss while maintaining a relatively simple overall device structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The transition section employs a periodic arrangement of gapped and ungapped segments along the optical path. This periodic structure creates repeated optical coupling opportunities that facilitate smooth mode transition and reduce abrupt discontinuities, leading to lower optical loss and improved signal integrity.

Inventive Principle:
Principle #19Periodic action

2Adaptability or versatility

If Y-Branch elements are cascaded to generate larger manifolds, then splitting ratio is increased, but cumulative loss becomes undesirable

Engineering Contradiction:
Improvesplitting ratioVSAvoidcircuit loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention changes the geometric parameters of the waveguide transition section by introducing alternating gapped and ungapped segments with specific gap widths and segment lengths. These parameter modifications optimize the optical coupling characteristics at each Y-Branch element, reducing the loss per element and thereby enabling cascaded structures to achieve high splitting ratios without excessive cumulative loss.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If waveguide imperfections are present, then manufacturing is easier, but energy is lost and signal integrity is diminished

Engineering Contradiction:
Improvewaveguide fabricationVSAvoidsignal integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The alternating gapped and ungapped segments create a structured transition that maintains optical mode equipotential surfaces throughout the waveguide transition. This ensures smooth mode propagation and reduces scattering losses caused by imperfections, thereby maintaining signal integrity while allowing for standard manufacturing processes.

Inventive Principle:
Principle #12Equipotentiality

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 design significantly reduces optical loss, achieving coupling efficiencies close to ideal levels, with improved stability and tolerance to wavelength and process variations, enabling more efficient optical signal splitting and routing in PLCs.

Implementation Method 1

optimizing the refractive delay, allowing for smoother splitting and improved coupling efficiency

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 2

a zero order mode in the curved waveguide couples into a first order mode in the input waveguide section

Methodology Applied
Scientific EffectOptical mode coupling: Waveguide (optics)

Data Source

PatentEP3612877B1Planar waveguide junction
Publication Date: 2023.07.12 NEOPHOTONICS CORP
  • EP3612877B1 patent drawingFigure 1~3
  • EP3612877B1 patent drawingFigure 4~6
  • EP3612877B1 patent drawingFigure 7~9

AI summary

Planar wavegiiide junctions are described with a waggled transition section connecting input waveguide sections with output waveguides sections, in which the waggled transitions have alternating segments matching the input waveguide and output waveguides to efficiently transition the optical signal. The planar waveguide junctions can be used to form efficient optical splitters, mixers, or taps.