Unusually high densification ⩽26% was obtained without lateral residual stresses within the laser beam waist inside porous glass during its multi-shot femtosecond laser irradiation, which may induce in the glass the related high refractive index change ~0.1. Corresponding laser irradiation regimes, resulting in such ultra-densification, decompaction and voids inside the glass, were revealed as a function of laser pulse energy and scanning rate, and were discussed in terms of thermal and hydrodynamic processes in the silica network.

Recent research in the field of formation of a 3D profile of optical elements with the use of direct laser writing at various wavelengths and photolithographic technologies on the basis of photomasks...

The spectroscopic detection of gases and their stable isotopes holds significant value in bio-sciences and climate studies. However, achieving high precision has long been confined to bulky and costly equipment. In this work, we introduce a nanophotonic waveguide that is capable of detecting CO₂ gas down to 20 parts per billion, and for the first time perform accurate stable isotope ratio measurements. The waveguide leverages a suspended membrane design with microstructured cladding, providing a high evanescent field confinement factor of 102%, moderate loss of 3.4 dB/cm, and effective suppression of etalons. The δ¹³C isotope ratio precision of 0.2‰ was achieved, replicating the performance of high-end laser absorption spectrometers. This marks the inaugural instance of on-chip, isotope-specific gas detection with a compact and cost-efficient system scalable to sensor networks.

Barriers were produced in porous glass through its local bulk density modification by direct femtosecond writing accompanied by СО₂-laser surface thermal densification, to make functional microfluidic elements separated by such physical barriers with different controlled permeability. The separation of multi-component solutions into individual components with different molecule sizes (molecular separation) was performed in this first integrated microfluidic device fabricated in porous glass. Its application in the environmental gas-phase analysis was demonstrated.