CC BY
0Femtosecond laser-induced periodic surface structuring of BaGa4Se7 crystal for near-infrared anti-reflection enhancement
A. Kuchmizhak1, A. Dostovalov2, S. Syubaev1*
1-Institute of Automation and Control Processes of the FEB RAS, 5 Radio str., Vladivostok, Russia
2- Institute of Automation and Electrometry of the SB RAS, 1 Acad. Koptyug Ave., Novosibirsk, Russia
* trilar@bk.ru
BaGa4Se7 (BGSe) crystal is a novel promising non-linear optical material for frequency conversion in the near- and mid-infrared ranges, characterizing by high nonlinear parameters, broadband transmission window and high laser damage thresholds [1]. Nevertheless, large Fresnel reflection losses, originating from refractive index difference between air and crystal media, limit the practical efficiency of BGSe. Thereby, the implementation of anti-reflective structures (ARs) is advantageous in reducing Fresnel optical loss from interface reflection, which in its turn make inexpensive and high-performing ARs fabrication techniques of high researcher's interest.
Femtosecond (fs) laser pulse processing has been justified as a powerful tool for nanostructures fabrication [2]. Being the one of the most common laser-induced nanomorphology, LIPSS (laser-induced periodic surface structures) were fabricated on almost all types of solid materials to modify surface properties, including colorization, super-hydrophobicity and anti-reflection.
Figure 1. Schematic illustration of LIPSS formation under femtosecond laser treatment of BGSe surface in the snake-like trajectory. Inset demonstrates Fourier-transform Infra-Red transmission spectra of unprocessed BGSe and LIPSS, fabricated on the one side of crystal.
Here, we demonstrate simple, high-performing and single-step fs-laser multi-pulse processing of BaGa4Se7 crystal surface. The resulting morphology represent subwavelength-periodic (~360 nm) LIPSS with nanotrench orientation, perpendicular to the irradiating laser beam polarization. The variation of experimental parameters (scanning speed, laser pulse fluence, pulse overlapping) was demonstrated to slightly effect on the LIPSS periodicity. Fourier-transform Infra-Red (FTIR) spectroscopy revealed the increased NIR transmittance of LIPSS-textured BGSe surface, compared to the untreated crystal.
This work was supported by Russian Science Foundation (grant. 23-22-00190).
[1] A. Yelisseyev, S. Lobanov, P. Krinitsin, L. Isaenko, The optical properties of the nonlinear crystal BaGa4Se7, Optical Materials, 99, 109564 (2020).
[2] G. Stephan, Formation of laser-induced periodic surface structures on different materials: Fundamentals, properties and applications, Advanced Optical Technologies, 11-39 (2020).
