Method and apparatus for measuring chromatic dispersion
AssigneeKddi Corporation
InventorsMichiaki Hayashi, Hideaki Tanaka
Life of this patent
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Abstract
A test signal light intensity-modulated with a test data is generated and enters the optical transmission line. An extractor extracts the first and second optical components from the test signal light output from the optical transmission line, the first and second optical components composed of any one of a main signal light component, an upper sideband component, and/or a lower sideband component. A time difference measuring apparatus measures a time difference between the first and second optical components. A converter converts the measured time difference into a chromatic dispersion value.
Claims16
A method to measure a chromatic dispersion in an optical transmission line, the method comprising:
- generating a test signal light intensity-modulated with a test data;
- inputting the test signal light to the optical transmission line;
- extracting first and second optical components from the test signal light output from the optical transmission line, each of the first and second optical components comprising one of the group consisting of a main signal light component of the test signal light, an upper sideband component of the test signal light, and a lower sideband component of the test signal light;
- measuring a time difference between the first and second optical components;
- and converting the measured time difference into the chromatic dispersion value, wherein the measuring a time difference between the first and second optical components comprises delaying the second optical component and calculating a correlation between the first optical component and the delayed second optical component while varying a phase difference between the first and second optical components.
A chromatic dispersion measuring apparatus for measuring a chromatic dispersion in an optical transmission line, the apparatus comprising:
- an extractor to extract first and second optical components from a test signal light output from the optical transmission line, each of the first and second optical components comprising one of the group consisting of a main signal light component of the test signal light, an upper sideband component of the test signal light, and a lower sideband component of the test signal light;
- a time difference measuring apparatus to measure a time difference between the first and second optical components;
- and
- a converter to convert the measured time difference into the chromatic dispersion value, wherein the time difference measuring apparatus comprises:
- a constant delay device to give a constant delay to one portion of the first and second optical components;
- a variable delay device to give a variable delay to another portion of the first and second optical components;
- an optical correlator to calculate a correlation between the first and second optical components delayed respectively by the constant delay device and the variable delay device;
- and
- a delay detector to detect a delay time of the variable delay device that brings a maximum correlation in the correlations that is calculated by the optical correlator.
Dependencies are inferred from the claim text.