Propagation of arbitrarily shaped femtosecond laser pulses through a photonic crystal fiber

We produce femtosecond optical pulses of different shapes to investigate the linear pulse propagation through a photonic crystal fiber in a regime where the conventional group velocity has no meaning and show that the temporal positions of centroid of energy are the same for both arbitrary pulses and transform-limited coherent pulses. By the concept of net group delay we explain the propagation delay for both the cases despite the fact that transmitted pulses suffer a severe distortion in the fiber. (c) 2006 American Institute of Physics.