Two-photon absorption coefficient determination with a differential F-scan technique

TL;DR

This paper introduces a modified differential F-scan technique for more accurate determination of two-photon absorption coefficients, simplifying the setup and improving measurement precision for materials like CdS, ZeSe, and CdSe.

Contribution

The paper presents a novel modification to the F-scan technique, enhancing accuracy and simplifying the experimental setup for two-photon absorption measurements.

Findings

Differential F-scan provides background-free signals.

The new fitting protocol improves measurement accuracy.

Validated measurements on CdS, ZeSe, and CdSe at 790 nm.

Abstract

In this paper we present a modification to the recently proposed transmission F-scan technique, the differential F-scan technique. In differential F-scan technique the programmed focal distance in the electronic-tunable lens oscillates, allowing the light detector of the setup to record a signal proportional to the derivative of the signal recorded with an F-scan. As for the differential Z-scan a background-free signal is obtained, but also the optical setup is simplified and the available laser power is double. We also present and validate a new fitting-procedure protocol that increments the accuracy of the technique. Finally, we show that fitting a signal from differential F-scan or the derivate of the signal of transmission F-scan is more accurate than simply fitting the signal from F-scan directly. Results from two-photon absorption at 790 nm of CdS, ZeSe and CdSe are presented.