Near-Infrared Saturable Absorption of Single-Wall Carbon Nanotubes Prepared by Laser Ablation Method

Abstract

We investigated the resonance dependence of saturable absorption (SA) properties in near-infrared in single-wall carbon nanotube (SWNT) materials prepared by the laser ablation method. For SWNT thin films coated on glass plates with a distinct single absorption band centered at 1.78 µm, we measured SA properties using the z-scan method with just- or weak-resonance excitation using a femtosecond laser at 1.78 µm or at 1.55 µm, respectively. In the just-resonance experiments the laser intensities of ∼50 MW/cm2 induced decreases in the absorption coefficient by ∼40%, but in the weak-resonance experiments one-order-higher laser intensities were necessary to obtain absorption changes of similar extents.