We present an experimental and numerical investigation of the quality factor degradation (&UDelta; 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 km) and very low dispersion slope (S-0 < 0.002 ps/nM(2) -km). 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 neither on fiber dispersion slope. &COPY; 2005 Elsevier B.V. All rights reserved.24941794451472