Gain enhancement in cascaded fiber parametric amplifier with quasi-phase matching: Theory and experiment

We report a novel gain enhancement scheme for fiber-optic parametric amplif iers utilizing cascaded amplification and quasi-phase matching (QPM), The t heory and method of QPM for four-wave mixing (FWM) are developed for the fi rst time to our knowledge. In experimental implementations of the theory, w e achieve >12 dB gain improvement in a three-stage dispersion-shifted (DS) fiber parametric amplifier. A 16-dB overall gain is obtained with 11 nm sep aration between zero-dispersion wavelength and pump wavelength. The experim ental results show good agreement with theory and simulations. The influenc e of QPM on spectral characteristics of parametric gain is investigated wit h numerical simulations.