ABSTRACT
Optical parametric amplification (OPA) is a phenomenon induced by nonlinear interaction among two or three lightwaves, in which signal light is amplified and light having a new frequency, called the “idler,” is generated from the pump light. OPA in fiber originates from third-order nonlinearity in glass materials. To obtain parametric gain, high pump power should be incident on the fiber. However, the incident power is limited by stimulated Brillioun scattering that scatters light in the backward direction. Suppressing such scattering is crucial for implementing fiber OPAs. The gain spectrum or bandwidth is an important characteristic for amplifiers. As in other optical amplifiers, the quantum limited noise figure is 3 dB in OPAs, which originates from spontaneous parametric fluorescence. The situation changed drastically in the early 1990s with the advent of erbium-doped fiber amplifiers, which make it possible to obtain high optical power from laser diode sources.
