Strong two-photon absorption in ErFeO3 thin films studied using femtosecond near-infrared Z-scan technique

Abstract

Ultrafast nonlinear optical (NLO) characterization of ErFeO3 thin films deposited by the solgel assisted spin coating technique is reported herein. In the present investigation, we have used femtosecond (fs) pulses for studying the nonlinear absorption and refraction properties of ErFeO3 thin films. Intensity dependent open and closed aperture Z-scan experiments were performed on ErFO3 films in the visible and near-infrared wavelengths of 600 nm, 800 nm, and 1200 nm. To explain the observed NLO results, phenomenological models of simultaneous multi-photon and excited sate absorption are developed for three-level model systems suitable for excitation wavelengths with (600 and 800 nm) and without (1200 nm) linear absorption, respectively. Optical limiting (OL) characteristic is shown to exist through the phenomenon of two-photon absorption in a certain intensity range at the three wavelengths and under the simultaneous saturation of linear absorption at 600 nm and 800 nm. The upper limit of the intensity for OL applications is demonstrated by the saturation effect. The non-linear absorption results are correlated with the linear absorption at these wavelengths, which involves electronic transitions between Fe d- and O p-orbitals.

Hexagonal RFeO3 (R = Dy, Er, and Lu) Films Grown on Glass Substrates with Both Magnetic and Ferroelectric Orders

“…Peak-like features were observed at approximately 2.4, 2.9, and 4.0 eV. The optical spectra are similar to those of previously reported for h-RFeO 3 35,38,39 but are different from those for o-RFeO 3 , 40 indicating that the obtained films had h-RFeO 3 phases. For epitaxial films of h-RFeO 3 (R = Er, Ho, Yb, and Lu), it was reported that the three peak-like features are assigned to the d−d transition in the Fe 3d orbital, the transition from the hybridized Fe 3d-O 2p to Fe 3d orbitals, and the charge-transfer transition from O 2p to Fe 3d orbitals, respectively.…”

Developing Push–Pull Hydroxylphenylpolyenylpyridinium Chromophores as Ratiometric Two-Photon Fluorescent Probes for Cellular and Intravital Imaging of Mitochondrial NQO1

“…Biological Application 1: A Vascular Labeling Experiment. To evaluate the two-photon performance of HBMP, its two-photon cross section (σ) was determined by a reported Zscan technique 33 using a femtosecond fluorescence spectrophotometer. The σ value was determined to be 70.5 GM at 800 nm (1 GM = 10 −50 cm 4 s photon −1 molecule −1 ) in PBS (Table S2), a higher value than that (65.2 GM) reported for HSMP bearing only one double bond, 25 highlighting the improvement in the two-photon performance by elongation of the conjugated links.…”