One-step measurement of optical fields in multimode circular fibers

We propose to determine the optical field in multimode circular fibers by u sing a one-step method that measures the Wigner distribution function of a section of the field in the fiber. This method allows an estimation not onl y of the power carried by each mode but also of the relative phases of diff erent modes in the fiber. An additional measurement with the same setup can even determine the propagation constants of different modes. An example is provided, and the connection of this method of field recovery to the coupl ing coefficient between fibers and light sources is also discussed. (C) 200 1 Optical Society of America.