Patent ID: 8699013
Filing Date: 2014-04-15
Classification: G01J,G01M

Abstract:
1. A chromatic dispersion measurement device comprising: an incident path that propagates a measured light signal incident from a measurement target, the incident path including an optical fiber having a polarization maintaining characteristic; a light branching unit configured to receive the measured light signal from a first input end connected to the incident path, divide the measured light signal incident from the input end into a first measured light signal and a second measured light signal, output the first measured light signal from a first output end and the second measured light signal having the same polarization direction as the first measured light signal from a second output end, and cause a frequency difference between the first measured light signal and the second measured light signal when the signals are output; a first branch path connected to the first output end, the first branch path propagating the first measured light signal, the first branch path including an optical fiber having a polarization maintaining characteristic; a second branch path connected to the second output end, the second branch path propagating the second measured light signal, the second branch path including an optical fiber having a polarization maintaining characteristic; an optical phase shifter provided in either one of the first branch path and the second branch path, the optical phase shifter periodically changing a phase α an optical combination unit configured to combine the first measured light signal incident from a second input end connected to the first branch path and the second measured light signal incident from a third input end connected to the second branch path, the optical combination unit outputting an interference element of an i-th optical component obtained by interference of the first measured light signal and the second measured light signal when the phase difference is the phase α a combination path connected to the third output end, the combination path including an optical fiber that propagates the combined measured light signal; a tunable band pass filter configured to receive the combined measured light signal from a fourth input end connected to the combination path, perform a sweep of a frequency in a frequency range for passing the combined measured light signal, perform frequency decomposition to extract a spectral component in the frequency range from the combined measured light signal, and output the result of the frequency decomposition as a measured component light signal from a fourth output end; an output light path connected to the fourth output end, the output light path including an optical fiber that propagates the measured component light signal; a light detection unit configured to receive the measured component light signal from a fifth input end connected to the output light path, converts the measured component light signal into an electrical signal, and uses the conversion result as an interference signal; and a control unit configured to perform a process of sequentially acquiring the interference signal corresponding to the i-th optical component in order of increase of i in one period in which the phase of the optical phase shifter is changed in synchronization with the sweep of the frequency in the frequency range.