A high confinement nonlinear optical fiber is provided along with methods of parametric amplification for use thereof. The nonlinear optical fiber may include a plurality of concentric layers which are configured to provide different guiding regimes to low-frequency and high-frequency components through transverse geometry and refractive index profiling, thus reducing waveguide dispersion. The resulting optical fiber provides a parametric device with phase-matching in any spectral region of interest, such that a fiber optic parametric amplifier (FOPA) implementing the optical fiber can amplify in any spectral window of interest. A narrow-band FOPA configured to minimize phase mismatching is also provided for use with the optical fiber, and may be implemented as a light source or a monochromator.