Multipump flattened-gain Raman amplifiers based on photonic-crystal fibers

Raman amplifiers based on photonic crystal fibers, whose cross section can be designed to enhance the nonlinear properties, have been investigated in this work. The use of multiple pumps is studied in order to flatten the amplifier gain spectrum, by varying their number, power, and wavelength, yielding a flatness as low as 0.5 dB in the wavelength range between 1540 and 1572 nm.