EXPERIMENTAL AND NUMERICAL INVESTIGATION OF SHORT-PULSE PROPAGATION AND AMPLIFICATION AROUND 1.3-MU-M IN A ND3++-DOPED FLUORIDE FIBER

We have investigated experimentally and theoretically the propagation and amplification characteristics of short optical pulses at lambda approximate to 1.3 mu m in a neodymium-doped fluorozirconate fiber: We have found that psec pulses (4 ps) with sub-nJ energies can be propagated and amplified without appreciable temporal and spectral reshaping. The propagation and amplification of sub-psec pulses (300 fs) of comparable energy, however, is significantly affected by the dispersive and nonlinear properties of the fiber. The interplay between dispersion and nonlinear effects leads to a power dependent pulse broadening which is more pronounced when the pulses are amplified. The experimental results are in good agreement with numerical simulations based on an extended version of the nonlinear Schrodinger equation. The comparison between experimental and numerical results allows to identify the pulse shaping mechanisms involved which is important in order to assess the potential of Nd3+-doped fluoride fibers as mode-locked fiber lasers and amplifiers.