Optical Transmission Device Suppressing Kerr Effect Distortion
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Solution Overview
Problem
The refractive index variation in optical fibers due to intensity changes in control signals causes phase or polarization modulation, leading to deterioration of transmission quality in optical communication systems.
Innovation Solution
An optical transmission device that generates a wavelength-multiplexed optical signal by intensity-modulating a first optical signal based on a control signal and a second optical signal based on a differential component between a constant-intensity signal and the control signal, which cancels out intensity variations, preventing phase or polarization modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a control signal with intensity variation is superposed on a data signal in an optical communication system, then remote control of optical relay or optical branching unit is enabled, but phase modulation or polarization modulation occurs due to refractive index variation, leading to deterioration of transmission quality
Solution Approach 1:
The patent applies preliminary anti-action by generating a differential component that is the inverse of the control signal's intensity variation. This differential component is added to the control signal before modulation, so that when both are transmitted through the optical fiber, their intensity variations cancel each other out, preventing refractive index changes and avoiding phase or polarization modulation that would deteriorate transmission quality
Solution Approach 2:
The patent changes the parameter representation of the control signal by transforming it into a differential component form. Instead of transmitting the control signal directly with its original intensity variations, the system transmits both the control signal and its differential component (inverted version), allowing the receiver to reconstruct the original control signal while the transmitted signals collectively maintain constant intensity, thus eliminating Kerr effect-induced distortions
2Loss of information
If the intensity of the control signal is varied to encode control information, then control information transmission is achieved, but the refractive index of the optical fiber varies due to the Kerr effect, causing deterioration of transmission quality
Solution Approach 1:
The patent segments the control information transmission into two separate optical signals: one carrying the control signal and another carrying the differential component (inverted control signal). By dividing the transmission into these two segments that are later recombined at the receiver, the system maintains constant overall intensity while still encoding and transmitting the control information effectively
Solution Approach 2:
The patent converts the harmful intensity variation into a beneficial arrangement by creating a differential component that mirrors the control signal's variations in reverse. This transformation allows the intensity variations that would normally cause harm (refractive index changes and phase modulation) to instead serve as a mechanism for maintaining constant overall intensity when both signals are transmitted together, thereby eliminating the harmful Kerr effect while preserving control information
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 effectively suppresses the deterioration of transmission quality by maintaining constant light intensity in the wavelength-multiplexed signal, even with varying control signal intensities, thereby ensuring stable optical signal propagation.
Implementation Method 1
a first optical modulator configured to intensity-modulate an optical signal depending on the control signal, the first optical modulator configured to output a first optical signal
Implementation Method 2
The optical fiber used for propagating the optical signal has the property that a refractive index thereof varies depending on the intensity of the optical signal (Kerr effect)
Data Source
AI summary
It is intended to suppress the deterioration of the transmission quality of an optical signal propagating through an optical fiber due to the intensity variation of a control signal.An exemplary aspect of the present invention includes outputting main signal light; generating a first optical signal by intensity-modulating an optical signal depending on a control signal; generating a second optical signal by intensity-modulating an optical signal depending on a differential component between a prescribed signal having a constant intensity and the control signal; outputting a wavelength-multiplexed optical signal by multiplexing the first optical signal being generated and the second optical signal being generated; and transmitting a transmitting signal by multiplexing the output main signal light being output and the wavelength-multiplexed optical signal being output.