Micro-to-Nanoscale Characterization of Femtosecond Laser Photo-Inscribed Microvoids
Matilde Sosa, Maxime Cavillon, Thomas Blanchet, Gergely Nemeth, Ferenc Borondics, Guillaume Laffont and Matthieu Lancry
Nanomaterials (2024)
Fiber Bragg gratings are key components for optical fiber sensing applications in harsh environments. This paper investigates the structural and chemical characteristics of femtosecond laser photo-inscribed microvoids. These voids are at the base of type III fs-gratings consisting of a periodic array of microvoids inscribed at the core of an optical fiber. Using high-resolution techniques such as quantitative phase microscopy, electron transmission microscopy, and scattering-type scanning near-field IR optical microscopy, we examined the structure of the microvoids and the densified shells around them. We also investigated the high-temperature behavior of the voids, revealing their evolution in size and shape under step isochronal annealing conditions up to 1250 °C.