Nonlinear-index-of-refraction measurement in a resonant region by the use of a fiber Mach-Zehnder interferometer.

The nonlinear index of refraction in a resonant region has been determined by the use of a fiber-based Mach--Zehnder interferometer to measure the temporal fringe shift between two signals. The measurement technique is direct and does not require additional amplitude information for the extraction of the nonlinear index of refraction. This technique has been used to measure the temporal response of an InGaAsP semiconductor optical amplifier at 1.313 µm.