Sn O 2 nanoparticles in silica: Nanosized tools for femtosecond-laser machining of refractive index patterns

Abstract

We show that SnO 2 nanoclusters in silica interact with ultrashort infrared laser pulses focused inside the material generating a hydrostatic compression and photoelastic response of the surrounding glass. This effect, together with the laser-induced nanocluster amorphization, gives rise to positive or negative refractive-index changes, up to 10 −2 , depending on the beam-power density. This result points out a wide tuning of the refractive index patterns obtainable in silica-based optical technology.

Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices

“…We underlined that the proposed synthesis method is not limited to the production of NS films on silicon substrates, but is instead applicable to other thermally stable substrates such as quartz for producing transparent functional films on transparent media that can be further processed into waveguides or other optical patterns, thanks to the photorefractive response of the NS material 46 Oxide nanocrystals (Methods and Supplementary Fig. S4).…”

“…As a result of the strongly localized energy release, partial amorphization of the nanophase takes place in the glass 28 , accompanied in some cases by local compaction of the surrounding host 46 . Nanophase amorphization and host compaction are concomitant mechanisms (tunable by changing the laser power density) that may be used to induce local permanent modification of the refractive index up to approximately ± 10 − 2 , either positive or negative depending on the process parameters 46 . Importantly, this type of top-down processing is entirely implementable to the proposed bottom-up strategy of material synthesis, thus allowing for the design of a wide class of optoelectronic devices.…”

“…The different energy gap of the NCs and the host, together with the chemical stability of the whole system, enable the use of a direct photo-writing process for the fabrication of refractive index patterns by exposure to focused laser beams. In NS SnO 2 :SiO 2 , laser pulses in the nearinfrared, visible and near-UV spectral regions, are selectively absorbed by the NCs in the transparency region of the glass matrix through direct or multi-photon absorption processes 28,46,47 . As a result of the strongly localized energy release, partial amorphization of the nanophase takes place in the glass 28 , accompanied in some cases by local compaction of the surrounding host 46 .…”

“…In NS SnO 2 :SiO 2 , laser pulses in the nearinfrared, visible and near-UV spectral regions, are selectively absorbed by the NCs in the transparency region of the glass matrix through direct or multi-photon absorption processes 28,46,47 . As a result of the strongly localized energy release, partial amorphization of the nanophase takes place in the glass 28 , accompanied in some cases by local compaction of the surrounding host 46 . Nanophase amorphization and host compaction are concomitant mechanisms (tunable by changing the laser power density) that may be used to induce local permanent modification of the refractive index up to approximately ± 10 − 2 , either positive or negative depending on the process parameters 46 .…”

Directly photoinscribed refractive index change and Bragg gratings in Ohara WMS-15 glass ceramic

“…Chiodini et al [25,26] reported unpatterned permanent changes in the refractive index of tin-silicate glass ceramic exposed to UV radiation. Paleari et al [27] reported refractive index patterning in a tin-silicate glass ceramic using an 800 nm femtosecond laser.…”