Broadband 2x2 Optical Splitter Power Balance Stability

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Solution Overview

Problem

Conventional 2x2 optical splitters struggle to maintain a stable power balance ratio over a wide fractional bandwidth of wavelengths, limiting their effectiveness in fiber-optic networks that require wavelength-insensitive performance for broadband applications.

Innovation Solution

The development of four-port optical waveguide elements that distribute optical power from one or two inputs into two outputs with a substantially constant power balance ratio over a wide fractional bandwidth, utilizing a combination of crossover and non-quadrature components with specific optical path lengths and coupling coefficients to achieve stable splitting across the ultra-broad wavelength range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional 2x2 optical splitters are used, then the device structure is simple and easy to manufacture, but the power balance ratio cannot be maintained stable over a wide fractional bandwidth of wavelengths

Engineering Contradiction:
Improvepower balance ratio stabilityVSAvoidwavelength bandwidth
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The optical splitter is divided into multiple functional sections: a first directional coupler section, a second directional coupler section, and intermediate waveguide sections. Each section has specific coupling coefficients and path length differences that work together to achieve broadband wavelength insensitivity while maintaining power balance ratio stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs specific parameter configurations including coupling coefficients (k1, k2, k3, k4), path length differences (ΔL1, ΔL2, ΔL3), and waveguide dimensions that are optimized to maintain consistent power splitting across a wide wavelength range from 1260nm to 1625nm, achieving both reliability and adaptability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the optical path length difference is increased to improve wavelength insensitivity, then the power balance ratio becomes more stable, but the device size increases

Engineering Contradiction:
Improvewavelength insensitivityVSAvoidoptical path length
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The patent uses moderate path length differences (ΔL1, ΔL2, ΔL3) that are sufficient to achieve the required wavelength insensitivity and power balance stability without unnecessarily increasing the device size. The coupling coefficients are optimized to work effectively with these partial path length differences.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

Specific parameter optimization allows the device to achieve wavelength insensitivity with controlled path length differences. The coupling coefficients and path length differences are precisely tuned to maintain power balance ratio stability across the ultra-broad wavelength range while keeping the device compact.

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

These devices provide a power splitting tolerance of ±1 dB or less over the ultra-broad wavelength range of 1.25µ to 1.65µ, enabling efficient and stable operation in fiber-optic networks, particularly in Passive-Optical-Networks (PONs), by maintaining a balanced splitting ratio across a broad range of wavelengths.

Implementation Method 1

a first directional coupler having an first input, a first output, a second directional coupler having a second input, a second output, and a third directional coupler having a third input, a third output

Methodology Applied
Scientific EffectOptical coupling: Waveguide (optics)

Data Source

PatentEP1987382B1Broadband 2x2 optical splitter
Publication Date: 2022.04.20 NEOPHOTONICS CORP
  • EP1987382B1 patent drawingFigure 1~2
  • EP1987382B1 patent drawingFigure 3~4
  • EP1987382B1 patent drawingFigure 5~6

AI summary

An optical device containing a four-port optical mixer capable of distributing the optical power presented at either or both of two input ports to specified ratios in two output ports.