Broadband nonlinear optical and optical limiting effects of partially unzipped carbon nanotubes

Many studies have shown that both carbon nanotubes (CNTs) and graphene are important broadband nonlinear optical (NLO) and optical limiting (OL) materials. As hybrids of CNTs and graphene, partially unzipped carbon nanotubes (PUCNTs) can be expected to exhibit superior NLO and OL effects. In this work, PUCNTs were obtained through lengthwise cutting and unraveling of multi-walled carbon nanotubes. The structure and component of PUCNTs were confirmed by transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared and Raman spectra. NLO and OL properties were investigated by the Z-scan technique at both 532 and 1064 nm in the nanosecond regime, in comparison with CNTs and graphene. A remarkable enhancement was observed, which can be attributed to the synergistic effect of nonlinear scattering and nonlinear absorption.