All-fiber filter for efficient dispersion compensation

A dispersive filter is proposed that is based on the coupling, with a chirped periodic perturbation, of two copropagating waveguide modes that have different group velocities. Numerical calculations show that a nearly constant dispersion can be obtained over the filter bandwidth. Pulse recompression by a factor of 10 or more is possible. The filter could be made with photoinduced refractive-index gratings in optical filters.