Effect of femtosecond laser irradiation on structure‐terahertz property relationship in sodium borosilicate glasses

Abstract

We report the effect of high‐repetition rate femtosecond (fs) laser irradiation on structure‐terahertz (THz) property relationship for sodium borosilicate glasses. We have used nuclear magnetic resonance (NMR), terahertz time‐domain spectroscopy (THz‐TDS), and Raman spectroscopy to examine pristine and laser irradiated regions of these glasses to determine and quantify boron speciation, THz refractive index, n(THz), and change (Δn) in n(THz), and spectral, that is, structural, changes due to laser exposure, respectively. Our results suggest that laser irradiation‐induced Δn(THz) values are dependent upon the glass composition, structural units, connectivity, and network, for example, the corresponding K‐ and R‐values of the borosilicate glass. Depolymerized glass networks show no changes in NMR B4 signal, slight changes in Raman spectral changes related to silicate structural units, for example, increase in Q3 tetrahedra with one nonbridging oxygen (nbO) atom, and higher measurable n(THz) and Δn(THz). More polymerized glasses, on the other hand, show changes in NMR B4 signal, varying degrees of Raman spectral changes in the borate subnetwork and structural units, and lower n(THz) and Δn(THz). The THz refractive index is most sensitive to modifier ions in the glasses, which are directly responsible for nbO formation, glass structure, and network polymerization.

A perspective on recent developments of structure‐terahertz property relationships in glasses

“…12 Recently, we have completed our comprehensive study of glass structure-THz property relationships for the borosilicate, tellurite, and chalcogenide glass families. [13][14][15][16][17][18][19] Figure 2 shows the refractive index and absorption coefficient across the THz bandwidth and the 0.5 THz absorption coefficient and refractive index correlation for these glasses. 18 This data demonstrates that glass chemistry, composition, and structure impact resulting properties at THz frequencies, as it would impact any other properties, that is, optical (at visible frequencies), mechanical, and thermal.…”

“…The black and red refractive index points represent pristine and laser-irradiated glasses, respectively. 15 useful for developing active and passive components for applications across these frequencies.…”

“…Finally, we have studied the effect of high-repetition-rate fs laser irradiation on the structure-THz property relationship in the sodium borosilicate system by examining pristine and laser irradiated regions using NMR to quantify boron speciation, THz-TDS to measure the THz refractive index and change (Δn), and Raman spectroscopy to examine glass structure changes induced by fs laser exposure. 15 We determined the glass composition, connectivity, and network (R-value) of borosilicate glass are critical for fs laser irradiated structure and property changes.…”

Structural, optical, and cytotoxicity studies of laser irradiated ZnO doped borate bioactive glasses

“…The effect of laser irradiation was studied for borosilicate glasses attracted much of scientisits attention because it can stimulate various microspheres that can be controlled within transparent materials due to non-linear optical absorption 46 , 47 . The novelty in the work is to study the effect of laser irradiation on the structure and optical properties of ZnO doped borate bioactive glass.…”