Dispersion-modified actively modelockederbium fibre laser using a chirped fibregrating

The authors describe the operation of an actively modelocked Er fibre laser incorporating a chirped in-fibre Bragg reflection grating as one end mirror to the cavity, acting as a lumped, highly dispersive element. In one orientation the grating shifted the cavity into the normal dispersion regime, and pulses of ~25 ps duration were produced. In the opposite orientation, the cavity dispersion was anomalous and ~8 ps pulses were produced with characteristics typical of solitons propagating in a periodically perturbed system.