Affiliation:
1. Castellini Officine Meccaniche
2. Istituto Nazionale di Ottica - Consiglio Nazionale delle Ricerche (INO-CNR)
3. Università degli Studi di Brescia
4. Università Cattolica del Sacro Cuore
5. CNRS, Université Claude Bernard Lyon1, Institut Lumière Matière
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 settings.
Funder
European Commission
Ministero dell’Istruzione,
dell’Università e della Ricerca
Università Cattolica del Sacro
Cuore