0619295 - ÚFP 2026 RIV US eng J - Journal Article
Lukeš, Jakub - Hájková, Věra - Hlubučková, Martina - Kanclíř, Vít - Žídek, Karel
Sensitive detection of Si3N4 thin-film defects via second harmonic generation microscopy.
Optics Letters. Roč. 50, č. 6 (2025), s. 1885-1888. ISSN 0146-9592. E-ISSN 1539-4794
R&D Projects: GA MŠMT(CZ) EH22_008/0004573
Institutional support: RVO:61389021 ; RVO:68378271
Keywords : laser irradiation * optical systems * SHG mapping
OECD category: Optics (including laser optics and quantum optics); Fluids and plasma physics (including surface physics) (FZU-D)
Impact factor: 3.1, year: 2023 ; AIS: 0.733, rok: 2023
Method of publishing: Open access
Result website:
https://opg.optica.org/ol/fulltext.cfm?uri=ol-50-6-1885&id=568913DOI: https://doi.org/10.1364/OL.553380

Optical coating, an integral part of many optical systems, is prone to damage from environmental exposure and laser irradiation. This underscores the need for reliable and sensitive coating diagnostics. We introduce second harmonic generation (SHG) as a method for the sensitive detection of defects and inhomogeneities within optical thin films. We demonstrate the use of SHG on Si3N4 layers tested for their laser-induced damage threshold. The SHG mapping was compared with commonly used diagnostic techniques, including Nomarski microscopy, white light interferometry, and electron microscopy. Owing to its sensitivity to variations in local symmetry, SHG is able to discern minute alterations in material composition, mechanical stress, and interface structures. Therefore, SHG identified modifications in the tested layers, highly extending the damage recognized by standard methods. Furthermore, we demonstrate SHG’s ability to enhance specific features by modulation of incidence angles and polarization modes. Based on these findings, we propose SHG as an ideal diagnostic tool for the early identification of laser-induced modifications in centrosymmetric thin films.
Permanent Link: https://hdl.handle.net/11104/0366046