DC two-photon absorption signal offset and intensity autocorrelation amplitude comparison in the femtosecond pulse focusing of lenses with spherical aberration

Abstract

In this work we theoretically confirm that the constant term of the measured signal of the Fringe-Resolved Autocorrelation technique using a two-photon absorption photodiode as sensor provides the same information as the intensity autocorrelation amplitude obtained from this technique. We achieve this result by computing the temporal intensity pulse distributions of focused femtosecond pulses around the focal region of an aberrated system and calculating both the intensity autocorrelation and the quadratic interferometric autocorrelation equation. Pulses with initial Full-Width Half-Maximum pulse widths of 50.0 and 20.0 [fs] were focused with a BK7 double convex lens.