Fiber-optical parametric amplifier with 70-dB gain

A record optical fiber gain of 70 dB was obtained in a continuous-wave pumped fiber-optical parametric amplifier. Limitations due to saturation effects from amplified spontaneous emission (ASE) and due to stimulated Brillouin scattering in this unidirectional amplifier are discussed. The spectral density of ASE was up to 180 mW/mn in agreement with theoretical expectations, illustrating the possible use as a high brightness optical noise source.