Optically modified second harmonic generation in silicon oxynitride thin films via local layer heating

0578067 - ÚFP 2024 RIV US eng J - Journal Article
Lukeš, Jakub - Kanclíř, Vít - Václavík, Jan - Melich, Radek - Fuchs, U. - Žídek, Karel
Optically modified second harmonic generation in silicon oxynitride thin films via local layer heating.
Scientific Reports. Roč. 13, č. 1 (2023), č. článku 8658. ISSN 2045-2322. E-ISSN 2045-2322
R&D Projects: GA MŠMT(CZ) EF16_026/0008390; GA ČR(CZ) GA23-08020S
Institutional support: RVO:61389021
Keywords : silicon nitride * strong second harmonic generation * thin films
OECD category: Coating and films
Impact factor: 4.6, year: 2022
Method of publishing: Open access
https://www.nature.com/articles/s41598-023-35593-8

Strong second harmonic generation (SHG) in silicon nitride has been extensively studied—among others, in terms of laser-induced SHG enhancement in Si3N4 waveguides. This enhancement has been ascribed to the all-optical poling induced by the coherent photogalvanic effect. Yet, an analogous process for Si3N4 thin films has not been reported. Our article reports on the observation of laser-induced threefold SHG enhancement in Si3N4 thin films. The observed enhancement has many features similar to all-optical poling, such as highly nonlinear power dependence, cumulative effect, or connection to the Si3N4–Si interface. However, identical experiments for low-oxygen silicon oxynitride thin films lead to complex behavior, including laser-induced SHG reduction. Following a thorough experimental study, including the effects of repetition rate or pulse length, the observed results were ascribed to heat-induced SHG variation. In addition to revealing a new mechanism of laser-induced SHG variation, our results also provide a means to identify this mechanism.
Permanent Link: https://hdl.handle.net/11104/0347092