A study resulting from a collaboration between the Department of Energy and the Department of Physics, and supported by an interdisciplinary PhD, has been published as a cover article in the journal Advanced Optical Materials.

The study explains the origin of the superfast optical response of titanium nitride (TiN). This material, already known for its refractory properties, is also attracting increasing interest because of its fast response to photoexcitation and the possibility of controlling its optical and electronic properties during synthesis.  

TiN films have already been used for thermo-photovoltaic devices, artificial photosynthesis or micro-supercapacitors on chips. In addition, TiN is compatible with technologies used in digital electronics. All in all, it is a material with great potential for the development of ultrafast photonic devices.

The study was carried out thanks to the synergy between two departments at the Polytechnic: TiN films were prepared in the NanoLab (Micro and Nanostructured Materials Lab) of the Energy Department, then characterised in the ultrafast spectroscopy laboratories of the Physics Department, and the experimental data were interpreted using a model developed in the Physics Department.

This collaboration has made it possible to study in depth a material of great technological interest and to clarify the origin of its peculiar response to light excitation, which can be manipulated by the manufacturing process,

explains Prof. Margherita Zavelani Rossi, co-author of the article.

Thanks to the accurate numerical model developed, it is now possible to determine how the response of a titan nitride thin film can be controlled by light itself; a fundamental knowledge for the development of new miniaturised optoelectronic and photonic devices,

adds Prof. Giuseppe Della Valle, co-author of the paper.

The experimental results mentioned in the article are also part of the METAFAST project, funded by the European Union’s H2020-FET-OPEN programme and coordinated by Prof. Giuseppe Della Valle. The project aims to develop a new class of ultrafast optical devices based on special nanostructured surfaces (called nonlinear metasurfaces).

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The study, signed by Silvia Rotta Loria, Beatrice Roberta Bricchi, Andrea Schirato, Luca Mascaretti, Cristina Mancarella, Alberto Naldoni, Andrea Li Bassi, Giuseppe Della Valle and Margherita Zavelani-Rossi, is available online.