Patent ID: 6462863
Filing Date: 2002-10-08
Classification: G01M

Abstract:
A method of resolving polarization mode dispersion in a span of optical fiber, comprising the steps of:(a) launching into a first end of the fiber, simultaneously, a first optical signal at a first wavelength and a second optical signal at a second wavelength such that the first and second wavelength are co-polarized at a first state of polarization to generate a first probe signal using a four wave mixing process in which two photons at the first wavelength combine with one photon at the second wavelength; (b) measuring the frequency of oscillations of the first probe signal as a function of distance in the fiber to generated a first measured dispersion map; (c) launching into the first end of the fiber, simultaneously, the first optical signal at the first wavelength and the second optical signal at the second wavelength such that the first and second wavelength are co-polarized at a second state of polarization to generate a second probe signal using a four wave mixing process in which two photons at the first wavelength combine with one photon at the second wavelength; (d) measuring the frequency of oscillations of the second probe signal as a function of distance in the fiber to generate a second measured dispersion map; and (e) deriving from the first and second measuring dispersion maps group velocities as a function of wavelength; and (f) calculating the difference between the group velocities of step (e) to obtain the polarization mode dispersion in the span of optical fiber.