Characterisation of nonlinear thin films using logarithmic Hilbert transform

A new technique based on logarithmic Hilbert transform processing of Maker-fringe curves to characterise second-order optical nonlinear depth profile of thin films is described and demonstrated experimentally. This technique, being analytical, is faster than its iterative alternative. This is the first time that a Hilbert transform based analytical tool has been applied to characterise nonlinear thin films.