Asymptotic analysis of the Z-scan trace to determine multiphoton absorption coefficients

We present a theoretical analysis of open aperture $Z$-scan signatures for materials exhibiting an absorption admixture of different multiphoton processes. Based on a polynomial expansion, we suggest some procedures to separate the contribution to the trace of the recorded transmittance made by absorptions of distinct order. The signal processing from experimental data allows a sequential estimation of assorted nonlinear absorption coefficients accurately.