Characterization of a photonic crystal fiber mode converter using low coherence interferometry.

The relative group delay of the different modes present in an all-fiber LP11 mode converter at a central wavelength of 750 nm is observed using low coherence interferometric imaging. We have simultaneously measured the relative group delay and computed the intensity and the phase distribution of the modes emitted from the mode converter end face using a Fourier technique, providing unequivocal identification of the modes involved.