Optical Line Testing Device Using Continuous Wave Signals
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Solution Overview
Problem
Conventional Optical Time Domain Reflectometers (OTDRs) face limitations in increasing dynamic range and resolution due to nonlinear effects caused by optical pulses, and the use of Erbium Doped Fiber Amplifiers is inappropriate for amplifying pulses with extreme power variations.
Innovation Solution
An optical line testing device employing a first and second wavelength tunable laser source generating optical signals with constant or continuous power, and an interferometer to produce an interference signal by varying the delay time, allowing for precise measurement of cutting positions in optical lines while minimizing nonlinear effects, enabling the use of an Erbium Doped Fiber Amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnitude of the optical pulse is increased to increase dynamic range, then the measurement distance is extended, but a nonlinear effect is generated causing measurement error
Solution Approach 1:
The patent changes the fundamental parameter of the optical signal from pulsed form to continuous wave form. By using a continuous wave optical signal instead of a pulsed optical signal, the system avoids the nonlinear effects that occur when increasing pulse magnitude, while still achieving extended dynamic range through continuous illumination and signal processing techniques.
2Reliability
If the length (width) of the optical pulse is increased to avoid nonlinear effect, then measurement accuracy is maintained, but the resolution of the OTDR deteriorates
Solution Approach 1:
The patent fundamentally changes the temporal parameter of the optical signal from pulsed to continuous wave. This eliminates the trade-off between pulse width and resolution, as the continuous wave approach maintains high resolution through frequency domain analysis and signal processing while providing stable, accurate measurements without the constraints of pulse width limitations.
3Device complexity
If conventional optical pulse method is used, then simple measurement is achieved, but Erbium Doped Fiber Amplifier cannot be used due to extreme power variations
Solution Approach 1:
The patent changes the optical signal from pulsed form with extreme power variations to continuous wave form with stable power levels. This parameter change enables compatibility with Erbium Doped Fiber Amplifiers, which cannot handle the extreme power variations in pulsed signals, while maintaining measurement functionality through continuous wave reflectometry techniques.
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 solution significantly improves dynamic range and resolution without sacrificing measurement accuracy, enabling precise detection of cutting positions on long-distance optical lines and minimizing nonlinear effects, thus allowing the use of optical amplifiers like EDFA.
Implementation Method 1
an interferometer configured to cause interference between a reflected optical signal, corresponding to the first optical signal, which is returning after having been emitted to the optical line, and the second optical signal to output an interference signal
Data Source
AI summary
An optical line testing device for measuring at least a cutting position of an optical line according to the present invention includes: a first wavelength tunable laser source configured to generate a first optical signal in which a plurality of wavelengths appear alternately and periodically; a second wavelength tunable laser source configured to generate a second optical signal which is identical to the first optical signal but has an adjustable delay time; and an interferometer configured to cause interference between a reflected optical signal, corresponding to the first optical signal, which is returning after having been emitted to the optical line, and the second optical signal to output an interference signal.