Simplifying asynchronous optical sampling: an experimental approach toward industrial integration exploiting lock-in acquisition

Year: 2024

Authors: Peli S., Tognazzi A., Franceschini P., Gandolfi M., Giannetti C., Ferrini G., Banfi F.

Autors Affiliation: Castellini Officine Meccan, Via Privata Giuseppe Castellini 2, I-25046 Cazzago San Martino, Italy; Univ Palermo, Dipartimento Ingn, Viale Sci Ed 10, I-90128 Palermo, Italy; Ist Nazl Ott Consiglio Nazl Ric INO CNR, Via Branze 45, I-25123 Brescia, Italy; Univ Brescia, Dipartimento Ingn Informaz, Via Branze 38, I-25123 Brescia, Italy; Univ Cattolica Sacro Cuore, Interdisciplinary Labs Adv Mat Phys I LAMP, Via Garzetta 48, I-25133 Brescia, Italy; Univ Cattolica Sacro Cuore, Dipartimento Matemat & Fis, Via Garzetta 48, I-25133 Brescia, Italy; Univ Claude Bernard Lyon 1, Inst Lumiere Matiere, FemtoNanoOpt Grp, CNRS, F-69622 Villeurbanne, France.

Abstract: Time-resolved optical spectroscopies are emerging as a go-to technique for non-destructive testing of nanomaterials. Inspecting the thermal and mechanical properties of a mesoscale device requires achieving delay times beyond the ns timescale in a nanoscopy setup, potentially in a vibration polluted environment. These requirements constitute a major challenge for traditional pump-probe techniques based on moving mechanical delay lines and lock-in detection. Asynchronous optical sampling (ASOPS) and electronically controlled optical sampling (ECOPS), avoiding any moving mechanical parts, are good alternatives. However, their detection scheme is based on fast-balanced photodiodes, which, as a technology, are not as widespread, not as developed, and lack the performance of lock-in based detection. In this study, we introduce what we believe is a novel approach that integrates ASOPS/ECOPS and lock-in detection methodologies, eliminating the necessity for a reference signal and streamlining the optical configuration. By leveraging the strengths of each technique, our approach enhances simplicity and efficiency. The scheme is first validated against standard approaches in the frame of a beam-depletion measurement in a sum frequency experiment. It is then tested in a paradigmatic case study to inspect the mechanics of a single gold nanodisk, with dimensions in the 100 nm range, nanopatterned on a sapphire substrate. These results widen the range of applicability of time-resolved optical techniques as a nano-metrology tool to industrial

Journal/Review: APPLIED OPTICS

Volume: 63 (23)      Pages from: 6086  to: 6096

More Information: European Commission (FESR o FSE, PON Ricerca e Innovazione 2 014-2020-DM 1062/2021, 20228YCYY7) ; Ministero dell’Istruzione, dell’Universit’a e della Ricerca (20172H2SC4\_005) ; Universit’a Cattolica del Sacro Cuore.
KeyWords: Phononic Crystals; Dynamics
DOI: 10.1364/AO.525546