Femtosecond ultrashort pulse generation by addition of positive material dispersion.

We demonstrate femtosecond ultrashort pulse generation by adding further positive group velocity dispersion (GVD) to compensate for the presence of positive GVD. The idea is based on the integer temporal Talbot phenomenon. The broad Raman sidebands with a frequency spacing of 10.6 THz are compressed to form a train of Fourier-transform-limited pulses by passing the sidebands through a device made of dispersive material of variable thickness.