Ultra-flat and broadband two-pump optical parametric amplifiers using a single-section highly nonlinear fiber

A broadband two-pump optical parametric amplifier with ultra-flat gain spectra is proposed in a single-section highly nonlinear fiber. By elaborately setting the dispersions and pump wavelength space, a gain over 250 nm with 0.02-dB uniformity is obtained. The pump polarizations and fiber length can be changed, achieving polarization-insensitive or higher gain, while the flatness and bandwidth of gain curve remain the same.