CC BY
2*
ALT'23 The 30th International Conference on Advanced Laser Technologies
N-I-24
Hierarchical multi-scale coupled periodical photonic nanopatterns inscribed in lithium niobate by femtosecond laser
M. Kosobokov1, S. Kudryashov12, A. Rupasov2, A. Akhmatkhanov1, G. Krasin2, P. Danilov1,2, B. Lisjikh1, A. Turygin1, A. Abramov1, E. Greshnyakov1, E. Kuzmin2,
M. Kovalev12, A. Efimov1, V. Shur1
1- School of Natural Sciences and Mathematics, Ural Federal University, 620000 Ekaterinburg, Russia 2- Lebedev Physical Institute, 119991 Moscow, Russia
E-mail: mihail.kosobokov@urfu.ru
The ultrafast interaction of tightly focused femtosecond laser pulses with bulk ferroelectric media in direct laser writing (inscription) regimes is known to proceed via complex multi-scale light, plasma and material modification nanopatterns, which are challenging for exploration owing to their mesoscopic, transient and buried character.
In this study, we report on the experimental demonstration and analysis of hierarchical multi-period coupled longitudinal and transverse microtracks and nanogratings in bulk lithium niobate inscribed in the focal region by 1030 nm, 300 fs laser pulses in the recently proposed sub-filamentary laser inscription regime [1]. The longitudinal Bragg-like topography nanogratings, possessing the laser-intensity-dependent periods ~ 400 nm, consist of transverse birefringent nanogratings, which are perpendicular to the laser polarization and exhibit much smaller periods «160 nm. The microtracks were imaged by optical microscopy. The nanoscale morphology of the microtracks was visualized at the sample cross-sections by atomic force microscopy (AFM).
Our analysis and modeling support the photonic origin of the longitudinal nanogratings, appearing as prompt electromagnetic and corresponding ionization standing waves in the pre-focal region due to interference of the incident and plasma-reflected laser pulse parts. The transverse nanogratings could be assigned to the nanoscale material modification by interfacial plasmons, excited and interfered in the resulting longitudinal array of the plasma sheets in the bulk dielectric material. Our experimental findings provide strong support for our previously proposed mechanism of such hierarchical laser nanopatterning in bulk dielectrics, giving important insights into its crucial parameters and opening the way for directional harnessing of this technology [2].
This research was funded by the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program).
[1] S. Kudryashov, A. Rupasov, M. Kosobokov, A. Akhmatkhanov, G. Krasin, P. Danilov, B. Lisjikh, A. Abramov, E. Greshnyakov, E. Kuzmin, M. Kovalev, and V. Shur, Hierarchical multi-scale coupled periodical photonic and plasmonic nanopatterns inscribed by femtosecond laser pulses in lithium niobate, Nanomaterials, vol.12, p.4303 (2022).
[2] S. Kudryashov, A. Rupasov, R. Zakoldaev, M. Smaev, A. Kuchmizhak, A. Zolot'ko, M. Kosobokov, A. Akhmatkhanov, and V. Shur, Nanohydrodynamic Local compaction and nanoplasmonic form-birefringence inscription by ultrashort laser pulses in nanoporous fused silica. Nanomaterials, vol.12, p.3613 (2022).
