Optical Multiplexing via Nonlinear Frequency Modulation

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Solution Overview

Problem

Current WDM techniques face limitations in achieving high-density multiplexing due to inaccuracies in setting wavelengths for signal lights and resolution issues in optical multiplexers and demultiplexers, restricting the number of optical signals that can be multiplexed.

Innovation Solution

An optical network system that includes a control light generator producing intensity-modulated light by combining two lights at different optical frequencies and modulating a carrier light in a nonlinear optical medium using the control light, enabling precise modulation and high-density multiplexing through frequency division multiplexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If WDM is used to multiplex optical signals with different wavelengths, then multiple information signals can be transmitted by one optical fiber, but the accuracy in setting wavelength for signal light and the resolution of optical multiplexer and demultiplexer are limited, making it difficult to realize high density multiplexing

Engineering Contradiction:
Improvenumber of optical signals multiplexedVSAvoidwavelength setting accuracy and optical multiplexer resolution
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent changes the modulation parameter from wavelength-based (WDM) to frequency-based modulation using intensity-modulated light. By modulating the intensity of light at different optical frequencies rather than relying on precise wavelength separation, the system achieves terahertz-level wide-band multiplexing without being constrained by multiplexer resolution limitations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/optical filtering system (multiplexer and demultiplexer with finite resolution) with a nonlinear optical medium that performs frequency multiplication. This substitution eliminates the bottleneck of mechanical resolution limits and enables higher density multiplexing through optical frequency conversion

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the number of optical signals multiplexed is increased to achieve high density, then more information can be transmitted, but the existing WDM system reaches its limit due to wavelength setting and multiplexer resolution constraints

Engineering Contradiction:
Improveinformation transmission capacityVSAvoidwavelength control precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent transitions from two-dimensional wavelength multiplexing (WDM) to three-dimensional multiplexing by combining frequency division multiplexing with intensity modulation. This adds a temporal dimension to the multiplexing scheme, allowing terahertz-level wide-band transmission that exceeds the capacity of traditional WDM systems

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

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 approach allows for terahertz-level wide-band multiplexing, enhancing the capacity to transmit multiple information signals with improved accuracy and density without requiring precise wavelength control between control and carrier lights.

Implementation Method 1

combines the control light with the carrier light for modulating the carrier light in a nonlinear optical medium in the transmission line by the control light

Methodology Applied
Scientific EffectNonlinear optical effect:

Implementation Method 2

The optical frequency conversion part carries out optical frequency conversion of the optical frequency multiplex signal by light wave mixing by a nonlinear effect

Methodology Applied
Scientific EffectLight wave mixing:

Data Source

PatentEP2424141B1Optical network system, optical multiplexing apparatus, and receiving apparatus
Publication Date: 2020.03.25 FUJITSU LTD
  • EP2424141B1 patent drawingFigure 1
  • EP2424141B1 patent drawingFigure 2
  • EP2424141B1 patent drawingFigure 3

AI summary

In an optical network system a carrier light propagates along a transmission line. A control light generator included in an optical multiplexing apparatus generates a control light obtained by modulating an intensity-modulated light by a data signal. A multiplexer combines the control light with the carrier light for modulating the carrier light in a nonlinear optical medium in the transmission line by the control light. The carrier light which propagates along the transmission line is modulated in the nonlinear optical medium on the basis of the control light.