Polarization-Independent Optical Waveform Shaping via Orthogonal Pumping

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Solution Overview

Problem

Conventional optical signal processing devices are inefficient in shaping waveforms and suppressing noise without depending on the polarization state of signal light, leading to significant losses and reduced efficiency, especially in optical circuits processing multiple signals with wavelength-division multiplexing.

Innovation Solution

An optical signal processing device incorporating a nonlinear optical medium with mutually orthogonal pumping lights and power controllers to achieve parametric amplification and gain saturation, independent of signal light polarization, using cascade-connected optical fibers and polarization controllers to ensure orthogonal polarization states for efficient waveform shaping and noise suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional optical signal processing devices are used for waveform shaping and noise suppression, then the device complexity is reduced, but the loss of energy increases and efficiency decreases

Engineering Contradiction:
Improveenergy lossVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The optical signal processing device is divided into multiple functional segments: a polarization beam splitter that separates orthogonal polarization components, multiple nonlinear optical media for parallel processing, and individual power controllers for each channel. This segmentation allows independent optimization of each processing path, reducing overall energy loss while maintaining manageable device complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention processes optical signals in the polarization dimension by separating orthogonal polarization components. Instead of processing all signals through a single path, the system utilizes the polarization degree of freedom to create parallel processing channels, thereby reducing energy loss through more efficient signal handling without significantly increasing complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If polarization-dependent optical signal processing is implemented, then the manufacturing precision is simplified, but the adaptability or versatility decreases

Engineering Contradiction:
Improvepolarization independenceVSAvoidpolarization control precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The device achieves polarization independence by creating a universal processing system that handles all polarization states equally. The polarization beam splitter divides the signal into orthogonal components that are processed through identical nonlinear optical media and power controllers, ensuring that the device functions effectively regardless of the input signal's polarization state, thus achieving multi-functionality across different polarization conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

While the overall system achieves polarization independence, each local processing channel maintains precise polarization control. The polarization beam splitter creates distinct polarization channels, and each channel's nonlinear optical media and power controllers are optimized for their specific polarization state, allowing high manufacturing precision at the component level while achieving versatility at the system level.

Inventive Principle:
Principle #3Local quality

3Reliability

If optical waveform shaping is performed using conventional methods, then the device complexity is maintained, but the optical signal quality deteriorates

Engineering Contradiction:
Improveoptical signal qualityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The optical signal processing device is divided into multiple functional segments: a polarization beam splitter that separates orthogonal polarization components, multiple nonlinear optical media for parallel processing, and individual power controllers for each channel. This segmentation allows independent optimization of each processing path, reducing overall energy loss while maintaining manageable device complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The polarization beam splitter acts as an intermediary that separates the input optical signal into orthogonal polarization components. This intermediary element enables subsequent nonlinear optical processing to occur on well-defined polarization states, improving the effectiveness of waveform shaping and noise suppression while maintaining a relatively simple overall device structure.

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 device effectively amplifies signal light with constant gain in orthogonal polarization directions, suppressing intensity noise and shaping waveforms without relying on signal light polarization, enhancing optical signal quality and efficiency in high-speed communication systems.

Implementation Method 1

The signal light is parametrically amplified by a control light pulse around the polarization direction of the control light pulse in the nonlinear optical medium

Methodology Applied
Scientific EffectParametric amplification:

Implementation Method 2

Wavelength-converted light is generated by four-wave mixing within the polarization maintaining fiber

Methodology Applied
Scientific EffectFour-wave mixing:

Implementation Method 3

The polarization controller controls the polarization direction of signal light

Methodology Applied
Scientific EffectPolarization control: Polarisation

Implementation Method 4

the optical S/N ratio depends on an amplified spontaneous emission (ASE) noise caused by an optical amplifier for compensating for the loss of an optical fiber

Methodology Applied
Scientific EffectAmplified spontaneous emission:

Data Source

PatentEP2187258B1Polarisation-independent optical waveform shaping device
Publication Date: 2011.06.22 FUJITSU LTD
  • EP2187258B1 patent drawingFigure 1
  • EP2187258B1 patent drawingFigure 2A~2B
  • EP2187258B1 patent drawingFigure 3

AI summary

An optical signal processing device has a nonlinear optical medium (1,2), first to fourth power controllers (11,12,13,14) and polarization controllers (11,12,13,14). To the nonlinear optical medium (1,2), signal light, and first to fourth pumping lights having wavelengths different from the signal light are input. The power controllers (11,12,13,14) are provided at the input side of the nonlinear optical medium, and control the powers of the first to fourth pumping lights so that a predetermined gain is obtained in the nonlinear optical medium (1,2). The polarization controllers (11,12,13,14) are provided at the input side of the nonlinear optical medium (1,2), and adjust the first to fourth pumping lights so that the polarization states of the first and the second pumping lights are mutually orthogonal, the polarization states of the third and the fourth pumping lights are mutually orthogonal, and the polarization state of the third pumping light makes an angle of 45 degrees with the polarization state of the first pumping light.