Picosecond laser writing of Ag−SiO2 nanocomposite nanogratings for optical filtering

• Published in: Optics and lasers in engineering 2020-01, Vol.124, Article 105840
• Main Authors: Andreeva, Yaroslava, Koval, Vladislav, Sergeev, Maksim, Veiko, Vadim P., Destouches, Nathalie, Vocanson, Francis, Ma, Hongfeng, Loshachenko, Anton, Itina, Tatiana E.
• Format: Article
• Language: English
• Subjects: Laser fabrication; Laser surface structuring; Nanocomposites; Nanoparticles; Silica glass
• ISSN: 0143-8166; 1873-0302
• DOI: 10.1016/j.optlaseng.2019.105840

•Single step ps laser writing allows precise formation of nanocomposite nanogratings.•The alignment of the periodic structure strongly depends on laser fluence.•Structural changes and phase transitions are caused by electrons’ injection from NPs.•The nanograting reflects differently when parallel or perpendicular to light incident plane. In this article, we propose a novel approach for dielectric nanograting fabrication by direct laser patterning. Possibilities of a well-controlled ultra-short laser recording of Ag-SiO2 nanocomposite gratings and their optical properties are examined. The mechanisms of laser processing involve silver nanoparticle growth in nanoporous silica glass films and laser interference-based formation of a periodic grating-like nanorelief. It is shown that laser energy should stay below the surface ”grooves” formation threshold for laser-inscription of the interference-based grating. Otherwise, another periodic structure oriented parallel to the incident laser polarization appears to erase the interference pattern. The parameter windows required for the controlled fabrication of the obtained structures are determined. The required threshold decay with the number of applied laser pulses is explained by a similarity in the roles of the nanoparticle absorption and surface defect accumulation typically leading to such dependencies. The optical properties of the obtained gratings are shown to depend on the angle between the incidence plane and the grating direction. When these directions coincide, a signal enhancement with a period-dependent blue-shift is revealed in the diffuse scattering spectra. When these directions are perpendicular, the signal is less enhanced, and a red shift is observed. The observed results are promising in short laser fabrication of different optical components, such as reflective optical filters.