Silica glass exhibits structural flexibility of the SiO4 network, enabling tunable optical properties under external stimuli. This study compares modifications induced by femtosecond laser direct writing (FLDW) and high-pressure/high-temperature (HPHT) treatment using confocal Raman spectroscopy, photoluminescence, and synchrotron X-ray diffraction. FLDW forms nanoscale periodic nanogratings with localized refractive-index changes, whereas HPHT promotes network densification via pressure-driven structural relaxation. The ultrafast non-equilibrium heating and quenching in FLDW generate defect configurations distinct from those formed under thermodynamic HPHT conditions, demonstrating a pathway for deterministic microstructural engineering of silica glass for advanced photonic applications. This study compares silica glass densification via high-pressure treatment and femtosecond laser. It reveals that laser irradiation creates unique structures with high-fictive temperatures and specific defects, enabling local optical tuning.
- Misora Tsubone
- Yasuhiko Shimotsuma
- Kiyotaka Miura