Femtosecond Laser Opening of Hollow-Filament Arrays: the Fiber Bragg Grating Opto-fluidic Sensor

Femtosecond laser irradiation followed by chemical etching (FLICE) was applied to standard telecommunication fiber, embedding an open-filament, grating array through the silica cladding and guiding core cross-section. Second and third order Bragg air-gratings are presented for the first time, providing nano-fluidic channels accessible to the outer cladding surface. Pishifted fiber Bragg grating responses to chemical etching were used to optimize a novel refractive index sensor for fluids.