Recent advances in the design and experimental implementation of fiber optical parametric amplifiers

Fiber optical parametric amplifiers (OPAs) are based on the third-order nonlinear susceptibility of glass fibers. If two strong pumps and a weak signal are fed into a fiber, an idler is generated. Signal and idler can grow together if pump power is high enough, and phase matching occurs. Gain in excess of 60 dB has been obtained. Fiber OPAs can exhibit a large variety of gain spectra: a gain bandwidth of 400 nm has been demonstrated; tunable narrowband gain regions can also be generated. The idler can be used for wavelength conversion, and spectral inversion. Fiber OPAs have a minimum NF of 3 dB, like EDFAs; this also holds when they are used as wavelength converters. By modulating the pump one can modulate the signal and/or idler at the output, and implement fast signal processing functions, including: demultiplexing of TDM signals; retiming and regeneration. The development of practical devices will require progress in the design and fabrication of fibers with high nonlinearity, dispersion properties suitable for improving phase matching and good longitudinal uniformity. Novel fibers, such as holey fibers, are promising in this respect.