Giant all-optical tunable group velocity dispersion in an optical fiber

We realize a strongly dispersive material with large tunable group velocity dispersion (GVD) in a commercially-available photonic crystal fiber. Specifically, we pump the fiber with a two-frequency pump field that induces an absorbing resonance adjacent to an amplifying resonance via the stimulated Brillouin processes. We demonstrate all-optical control of the GVD by measuring the linear frequency chirp impressed on a 28-nanosecond-duration optical pulse by the medium and find that it is tunable over the range ± 7.8 ns(2)/m. The maximum observed value of the GVD is 10(9) times larger than that in a typical single-mode silica optical fiber. Our observations are in good agreement with a theoretical model of the process.