Broadband Gain-Spectrum Measurement for Fiber Optical Parametric and Raman Amplifiers

We examine the use of a depolarized broadband probe to experimentally measure the gain spectra of amplifiers comprising parametric and Raman gain. The suggested technique allows a quick and accurate characterization of gain spectra spanning more than 100 nm. We derive formulas for processing spectral data to address polarization dependent gain and idler generation, and consequently develop a measurement methodology for obtaining reliable results. We demonstrate the viability of this approach by performing an experimental comparison with results obtained using tunable lasers. We expect the technique described here to be useful for fiber optical parametric amplifier development and characterization.