Optica Applicata, Vol. XXXIX, No. 2, 2009 Low cost incoherent pump solution for Raman fiber amplifier ANA M. ROCHA 1, 2 , BERTA NETO 1, 2 , MARGARIDA FACÃO 2 , PAULO S. ANDRÉ 1, 2* 1 Instituto de Telecomunicações, Campus de Santiago, 3810-193, Aveiro, Portugal 2 Departamento de Física da Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal * Corresponding author: pandre@av.it.pt In this work, we demonstrate the implementation of a low cost broadband pump source for Raman amplification. The advantages of this incoherent pumping scheme were demonstrated by compar- ing, experimentally and numerically, this solution with the one based on coherent pumping. We observed a decrease by 1.4 dB in the Raman gain ripple and a 16% increase in the bandwidth, for the latter solution. Keywords: Raman fiber amplifier, incoherent pump. 1. Introduction One of the most important challenges to the design of Raman fiber ampliers (RFA’s) is that of achieving a flat gain profile over a broad wavelength band, at a reasonable cost of implementation [1]. Typically, multiple pumps at different wavelengths are used to induce a flat gain in an ultra-wide bandwidth. In this type of amplifiers, the expected gain peak is shifted by 13.2 THz (≈ 100 nm in this spectral region) with respect to the pump signal frequency. Another option to enlarge the bandwidth of Raman amplifiers makes use of incoherent pumps. This approach has recently been proposed and the first experimental performance results show a 7 dB on/off gain with a gain ripple of approximately 0.8 dB over all the C spectral band [2]. Later numerical studies corroborate the above experimental results. They have also shown that the number of pumps needed to obtain the same gain flatness can be significantly reduced using incoherent pumping [3–5]. In addition, incoherent pumping has also the advantage of reducing nonlinear effects such as stimulated Brillouin scattering or four wave mixing induced by the pump-to-pump, pump-to-signal and pump-to-noise interaction [6].