Nonlinear optical absorption in nanoscale films revealed through ultrafast acoustics

Herein we describe a novel spinning pump-probe photoacoustic technique developed to study nonlinear absorption in thin films. As a test case, an organic polycrystalline thin film of quinacridone, a well-known pigment, with a thickness in the tens of nanometers range, is excited by a femtosecond lase...

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Bibliographic Details
Published inarXiv.org
Main Authors Chaban, Ievgeniia, Deska, Radoslaw, Privault, Gael, Trzop, Elzbieta, Lorenc, Maciej, Kooi, Steven E, Nelson, Keith A, Samoc, Marek, Matczyszyn, Katarzyna, Pezeril, Thomas
Format Paper
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 17.05.2022
Subjects
Acoustics
Fluence
Glass substrates
Lasers
Optical properties
Photon absorption
Photons
Signal processing
Thin films
Ultrasonic methods
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Summary:Herein we describe a novel spinning pump-probe photoacoustic technique developed to study nonlinear absorption in thin films. As a test case, an organic polycrystalline thin film of quinacridone, a well-known pigment, with a thickness in the tens of nanometers range, is excited by a femtosecond laser pulse which generates a time-domain Brillouin scattering signal. This signal is directly related to the strain wave launched from the film into the substrate and can be used to quantitatively extract the nonlinear optical absorption properties of the film itself. Quinacridone exhibits both quadratic and cubic laser fluence dependence regimes which we show to correspond to two- and three-photon absorption processes. This technique can be broadly applied to materials that are difficult or impossible to characterize with conventional transmittance-based measurements including materials at the nanoscale, prone to laser damage, with very weak nonlinear properties, opaque or highly scattering.
ISSN:2331-8422