Ultrafast laser-induced nanogratings in sodium germanate glasses

Femtosecond laser direct writing in SiO2‐Al2O3 binary glasses and thermal stability of Type II permanent modifications

“…Al 2 O 3 than for 30 mol% Al 2 O 3 in agreement with the reported values of glass melting T m temperatures.This could be attributed to an increase in Al coordination number (4, 5, and 6 fold-coordination25,26,27,28 ), increasing glass network cross-linking density and bond strength. Note that additional measurements of the viscosity-tempertaure dependence would be nice to validate this view.In addition based on nanogratings chemical changes observed in other multicomponent oxide glasses9,45,46 , we suggest that nanogratings in our aluminosilicate samples are made of Al 2 O 3 -rich phase that separates from the SiO 2 -rich matrix phase. Backscattered electron image…”

Femtosecond laser‐induced birefringent microdomains in sodium‐borate glass for highly secure data storage

“…The type II structure is characterized by the presence of hollow planes oriented perpendicular to the plane of polarization of the laser beam, and thus, it is similar to the nanograting structure obtained in other glasses, excluding some specific features. Traditionally, the thickness of planes in nanogratings is several tens of nanometers, and the period, in the case of one‐ and two‐component glasses, is about 200‐300 nm 1,11,14,15 . In sodium borate glass, the thickness of the planes turned out to be about 200 nm, and the period was 0.8 μm.…”

“…For a long time, silica glass was the only object for the investigation of the phenomenon of nanogratings. However, studies of the latest decade demonstrated the possibility of the formation of nanogratings in amorphous GeO 2 , 11 and a number of binary glasses of the GeO 2 –SiO 2 , 12 TiO 2 –SiO 2 , 13 Na 2 O–SiO 2 , 14,15 Na 2 O–GeO 2 16, 17 systems. For these glasses with a relatively simple composition, the nanoperiodical structure of the nanogratings is similar to that of the nanogratings forming in silica glass.…”

“…Moreover, the formation process is accompanied by the diffusion of alkaline cations both to the periphery of the modification region and to the boundaries of nanopores, thus the latter was manifested in the periodic distribution of alkali cations 14,16 . Increased energy is required for the formation of nanogratings in sodium germanate glasses with an alkali content of 10 mol.%, which lies in the region of the germanate anomaly 15 . The lower retardance was revealed in multicomponent glasses, which can be associated with a decrease in the period of nanogratings of up to 100 nm for AF32 glass 18 and 60 nm for Borofloat33 glass, 13 however, the reason for this phenomenon still being unknown.…”

Glass: Home of the Periodic Table

“…In recent years, studies on DLW of various structures in glasses have revealed a wide range of phenomena that occur when the material absorbs ultrashort pulses. These include local changes in the refractive index and writing of optical waveguides (Phillips et al, 2015), the formation of surface and bulk birefringent nanoperiodic structures (nanogratings) (Shimotsuma et al, 2003;Lotarev et al, 2019a), formation of micro-and nanobubbles (Bellouard and Hongler, 2011), local crystallization of non-linear phases in glass (Lipatiev et al, 2018b(Lipatiev et al, , 2020Lotarev et al, 2019b), precipitation of metal clusters, nanoparticles, and semiconductor quantum dots (Marquestaut et al, 2014;Shakhgildyan et al, 2018;Vetchinnikov et al, 2018;Hu et al, 2019). Despite the physical nature of the processes, involved in the interaction of laser pulses with glass, they lead to a local change in the chemical composition of glass by ions migrations to different areas of the laser affected zone.…”