Patent ID: 8229298

Claim:
A method for detecting dispersion, comprising: obtaining an electric signal within a predetermined bandwidth range from a received optical signal; obtaining an operated value of a power via an operation on the electric signal within the predetermined bandwidth range; and obtaining an amount of system dispersion according to a correspondence relationship between the operated value of the power and the amount of the system dispersion; wherein the electric signal within the predetermined bandwidth range is obtained with the steps of: (a) obtaining the electric signal through photoelectric conversion on the received optical signal; and (b) selecting the electric signal within the predetermined bandwidth range which has an upper border lower than a frequency value corresponding to a first minimum point of power spectrum density curve with dispersion; (c) selecting an optical signal within the predetermined bandwidth range which has the upper border lower than the frequency value corresponding to the first minimum point of the power spectrum density curve with dispersion; (d) obtaining the electric signal through the photoelectric conversion on the optical signal within the predetermined bandwidth range.