Gain profile measuring method and system and gain profile controlling method and system
AssigneesKDDI Submarine Cable Systems Inc., Mitsubishi Denki Kabushiki Kaisha
InventorsKiyoaki Takashina, Toshio Kawazawa, Koji Goto
Life of this patent
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Abstract
To control a gain profile in an optical fiber line to become a desirable form, a C-OTDR measuring apparatus (36) outputs a probe pulse light having a wavelength λm for an optical fiber line (14). A power level on the input or output side of a variable gain equalizer (22) can be measured according to a C-OTDR waveform of a return light of the probe pulse light entered through a C-OTDR path (20c) and an optical fiber line (16). By sweeping the measurement wavelength λm, the gain file is measured. The equalizing characteristics of the variable gain equalizer (22) are remotely controlled so that the gain profile becomes a desirable form according to the measured result.
Claims25
In an optical transmission system having first and second optical fiber lines, each of the first and second optical fiber lines transmitting a signal light in the opposite direction from the other, and a Coherent Optical Time Domain Reflectometry (C-OTDR) optical loop back circuit for optically connecting between the first and second optical fiber lines, a method for measuring a gain profile in the first optical fiber line, the method comprising:
- supplying the first optical fiber line with a plurality of laser lights, each of the plurality of laser lights having a different wavelength, and a probe pulse light having a measurement wavelength, the measurement wavelength being different from the wavelengths of the plurality of laser lights;
- measuring a power level of the probe pulse light at a predetermined position in the first optical fiber line from a return light of the probe pulse light entered through the C-OTDR optical loop back circuit and the second optical fiber line using C-OTDR;
- and
- performing the supplying and measuring steps while varying the measurement wavelength within a predetermined wavelength range.
In an optical transmission system having first and second optical fiber lines, each of the first and second optical fiber lines transmitting a signal light in the opposite direction from the other, and a Coherent Optical Time Domain Reflectometry (C-OTDR) optical loop back circuit for optically connecting between the first and second optical fiber lines, a system for measuring a gain profile in the first optical fiber line comprising:
- laser light generators to generate a plurality of laser lights, each of the plurality of laser lights having a different wavelength;
- a probe pulse light generator to generate a probe pulse light having a measurement wavelength, the measurement wavelength being variable within a predetermined wavelength range;
- an optical coupler to combine the plurality of laser lights output from the laser light generators and the probe pulse light and to output a combined light to the first optical fiber line;
- a measuring apparatus to measure a power level of the probe pulse light at a predetermined position in the first optical fiber line from a return light of the probe pulse light entered through the C-OTDR loop back circuit and the second optical fiber line using C-OTDR;
- and
- a controller to control the measuring apparatus so as to perform measurement within the predetermined wavelength range while varying the measurement wavelength within the predetermined wavelength range.
In an optical transmission system having first and second optical fiber lines, each of the first and second optical fiber lines transmitting a signal light in the opposite direction from the other, and a Coherent Optical Time Domain Reflectometry (C-OTDR) optical loop back circuit for optically connecting between the first and second optical fiber lines, a method for controlling a gain profile in the first optical fiber line, the method comprising:
- supplying the first optical fiber line with a plurality of laser lights, each of the plurality of laser lights having a different wavelength, and a probe pulse light having a measurement wavelength, the measurement wavelength being different from the wavelengths of the plurality of laser lights;
- measuring a power level of the probe pulse light at a predetermined position in the first optical fiber line from a return light of the probe pulse light entered through the C-OTDR optical loop back circuit and the second optical fiber using C-OTDR;
- storing the measured result of the measuring step within a predetermined wavelength range after operating the probe pulse supplying step and measuring step while varying the measurement wavelength within the predetermined wavelength range;
- and
- controlling equalizing characteristics of a variable gain equalizer disposed in the first optical fiber line according to the stored measured result.
In an optical transmission system having first and second optical fiber lines, each of the first and second optical fiber lines transmitting a signal light in the opposite direction from the other, and a Coherent Optical Time Domain Reflectometry (C-OTDR) optical loop back circuit for optically connecting between the first and second optical fiber lines, a system for controlling a gain profile in the first optical fiber transmission line comprising:
- a variable gain equalizer disposed in the first optical fiber line;
- laser light generators to generate a plurality of laser lights, each of the plurality of laser lights having a different wavelength;
- a probe pulse light generator to generate a probe pulse light, the probe pulse light having a measurement wavelength variable within a predetermined wavelength range;
- an optical coupler to combine the laser lights output from the plurality of laser light generators and the probe pulse light to output a combined light into the first optical fiber line;
- a measuring apparatus to measure a power level of the probe pulse light at a predetermined position in the first optical fiber line from a return light of the probe pulse light entered through the C-OTDR optical loop back circuit and the second optical fiber line using C-OTDR;
- and a controller to control the measuring apparatus so as to perform measurement within the predetermined wavelength range while varying the measurement wavelength within the predetermined wavelength range and to control the variable gain equalizer according to power levels of the plurality of measurement wavelengths measured on the predetermined position.
A method for measuring a gain profile in an optical transmission system, the method comprising:
- supplying a first optical fiber line with a plurality of laser lights, each of the plurality of laser lights having a different wavelength, and a probe light having a measurement wavelength, the measurement wavelength being different from the wavelengths of the plurality of laser lights;
- varying the measurement wavelength within a predetermined range;
- and
- measuring a power level of the probe pulse light at a predetermined position in the first optical fiber line from a return light of the probe pulse light passed through a Coherent Optical Time Domain Reflectometry (C-OTDR) optical loop back circuit and a second optical fiber line using C-OTDR.
Dependencies are inferred from the claim text.