Laser-Induced Deposition of Single-Walled Carbon Nanotubes in Suspended Core Optical Fibers

We experimentally demonstrate laser-driven deposition of single-walled carbon nanotubes (CNTs) in suspended core fibers (SCFs) for the first time. Three samples for each SCF type with three (SCF1) and four (SCF2) air holes are individually inserted in a syringe loaded with a 0.5 mL solution of CNTs dispersed in methanol, and a high-power laser at 980 nm is injected into the fibers during distinct periods: SCF1 (20, 30 and 45 minutes), SCF2 (5, 10 and 15 minutes). The CNT solution thermally expands, accelerating and depositing nanotubes on the fiber tip. The material and dimensions of the CNTs deposited on the SCFs' cross-section are characterized, revealing nanotube bundles increasing in thickness from the fiber core to the bridges and inside the holes. The results indicate that shorter laser periods increase nanotube distribution within the SCFs’ core and overall cross-section. In contrast, longer periods focus high-pressure particles, enhancing ablation and depositing thinner layers in the fiber core. These achievements are significant for nanoparticle deposition and for the fabrication of microscale devices on tips and within specialty and hollow fibers, enabling innovative fiber sensors, mode-locked fiber lasers, in-fiber acousto-optic modulators, and broadband photoacoustic transmitters for imaging and neurostimulation.