Q penalties due to pump phase modulation and pump RIN in fiber optic parametric amplifiers with non-uniform dispersion

Abstract

We present an experimental and numerical investigation of the quality factor degradation ($\Delta Q$) due to pump phase modulation and pump relative intensity noise (RIN) in single- and double-pumped fiber optical parametric amplifiers (FOPAs). These penalties are investigated in FOPAs constructed with fibers having constant and randomly varying zero-dispersion wavelength (${\lambda }_0$) along the fiber. We show that pump phase modulation in uniform fibers (constant ${\lambda }_0$) produces large $Q$ penalties, while in fibers with variations of ${\lambda }_0$, these penalties can be strongly reduced in both single- and double-pumped FOPAs. We also show that $Q$ penalties due to pump phase modulation tend to disappear in FOPAs made with very short fibers ($L<0.1\mathrm{km}$) and very low dispersion slope $S_0<0.002\mathrm{ps}{\mathrm{nm}}^{-2}{\mathrm{km}}^{-1}.$ The $Q$ penalties due to pump RIN, which for typical FOPA parameters are much smaller than those due to pump phase modulation, are also reduced in non-uniform fibers (varying ${\lambda }_0$), but do not depend on fiber length nor on fiber dispersion slope.