Investigation of the modifications properties in fused silica by the deep-focused femtosecond pulses

In this study, we demonstrate the elongated Type I modifications in fused silica with an axial length > 50 µm. Such extended longitudinal dimensions were obtained by deep focusing radiation of a femtosecond laser inside fused silica at a depth of 2 mm. The transition from the Type II modification...

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Veröffentlicht in:Optics express 2023-01, Vol.31 (3), p.4482-4496
Hauptverfasser: Stankevič, Valdemar, Karosas, Jonas, Račiukaitis, Gediminas, Gečys, Paulius
Format: Artikel
Sprache:eng
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Zusammenfassung:In this study, we demonstrate the elongated Type I modifications in fused silica with an axial length > 50 µm. Such extended longitudinal dimensions were obtained by deep focusing radiation of a femtosecond laser inside fused silica at a depth of 2 mm. The transition from the Type II modification (nanogratings) to the Type I modification (refraction index change) was observed with increasing focusing depth at the constant pulse energy. The refractive index changes of ∼ 1.5×10 for a single pass and 2.4×10 for multiple passes were demonstrated. The radial dimensions of the deep-focused modifications were confined to 0.5-1.5 µm size. By overlapping the modifications in radial and axial directions, 1D phase grating in the depth range from 2 to 5 mm was recorded, allowing to split of the beam with a diffraction efficiency of > 96%. We demonstrate that the aberration-based recording with a Gaussian beam in fused silica is a simple tool for fabricating complex phase diffractive optical elements.
ISSN:1094-4087
1094-4087
DOI:10.1364/OE.477343