Method and apparatus for measuring chromatic dispersion coefficient
AssigneeFujitsu Limited
InventorsKazuhiko Soeda, Masakazu Mori, Tsutomu Nishikawa, Kiyoshi Tomimori
Life of this patent
Estimating the term…
Abstract
A measuring system operated by an optical transmitter; an optical spectrum analyzing part receiving an input optical signal branched from the optical transmitter; an optical receiver for connecting with, via an optical fiber to be measured, the optical transmitter; and a data processing part operative to produce a chromatic dispersion coefficient to be measured, by comparing a calculated baseband characteristic, derived from data concerning the optical transmitter and the optical spectrum analyzing part, with an actual baseband characteristic obtained in the optical receiver.
Claims19
A method for measuring a chromatic dispersion coefficient comprising the steps of:
- (a) measuring an actual baseband characteristic of an optical fiber in accordance with a received optical signal level at an output end of the optical fiber, wherein the received optical signal corresponds to an input optical signal, having components of respective amplitudes in its optical spectrum corresponding to a plurality of oscillation modes, that is provided to an input end of the optical fiber, the input optical signal being modulated in amplitude with an AC signal which is varied to provide a plurality of modulation frequencies;
- (b) obtaining a calculated baseband characteristic having a profile fitting closest to the actual baseband characteristic, by using data concerning the wavelengths and amplitudes of said components corresponding to said oscillation modes in the optical spectrum of the input optical signal, data concerning the modulation frequencies, and data concerning a provisional chromatic dispersion coefficient;
- and
- (c) determining the provisional chromatic dispersion coefficient providing said closest fitting profile as the actual chromatic dispersion coefficient of the optical fiber.
A method for measuring a chromatic dispersion coefficient comprising the steps of:
- (a) projecting an input optical signal, having a plurality of components in its optical spectrum corresponding to a plurality of oscillation modes, onto one end of an optical fiber, the input optical signal being modulated by an AC signal which is varied to provide a plurality of modulation frequencies;
- (b) measuring an actual baseband characteristic through detection, by means of an optical receiver, of an output optical signal received at another end of the optical fiber corresponding to said input optical signal at each said modulation frequency;
- (c) detecting the wavelength and amplitude of each said component corresponding to each said oscillation mode of the input optical signal with the aid of an optical spectrum analyzing part;
- (d) deriving a calculated baseband characteristic fitting closest to the measured baseband characteristic, by using data concerning the modulation frequency, the wavelength and the amplitudes detected by the optical spectrum analyzer, and a provisional chromatic dispersion coefficient;
- and
- (e) determining the provisional chromatic dispersion coefficient providing said closest fitting of said actual and calculated baseband characteristics to be the actual chromatic dispersion coefficient of the optical fiber.
An apparatus for measuring a chromatic dispersion coefficient comprising:
- means for measuring an actual baseband characteristic of an optical fiber in accordance with the level of an output optical signal received at an output end of the optical fiber, the output optical signal corresponding to an input optical signal having a plurality of components corresponding to respective oscillation modes in its power spectrum and which is provided to an input end of the optical fiber, the input optical signal being modulated in amplitude with an AC signal which is varied to provide a plurality of modulation frequencies;
- and
- means for obtaining a calculated baseband characteristic having a profile fitting closest to the measured actual baseband characteristic, by using data concerning the wavelengths and amplitudes of each of said components corresponding to said oscillation modes of the input optical signal, data concerning the modulation frequencies, and data concerning a provisional chromatic dispersion coefficient;
- wherein the value of the provisional chromatic dispersion coefficient providing said closest fitting profile is determined to be the actual chromatic dispersion coefficient of the optical fiber.
Dependencies are inferred from the claim text.