Optical materials

Distribution of NBOHC color centers in birefringent microtracks induced by laser radiation in the bulk of fused silica

A. E. Rupasov, G. K. Krasin, Yu. S. Gulina, I. D. Matyaev, S. I. Kudryashov

P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow

Abstract: This study presents the first investigation of the distribution of non-bridging oxygen hole centers (NBOHCs) within birefringent microtracks in fused silica and correlates it with their spatial structure. A photoluminescence band peaking at 650 nm, associated with NBOHC formation, was identified, and the dependence of its integrated intensity on the longitudinal coordinate along the microtrack was determined. Micron-scale structure in the microtrack cross-section was detected via photoluminescence signals from these centers. The dependence of microtrack birefringence magnitude $(\Delta n\sim 10^{-3})$ on laser pulse energy density was established. Mechanisms of fused silica modification were determined using Raman spectroscopy.

Keywords: direct laser writing, femtosecond laser pulses, silica, nanogratings.

DOI: 10.61011/OS.2025.06.60919.7595-25

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