Studies On Optical Limiting Of Dispersible MWCNTs/TiO₂ Nanocomposite

The various researchs on the optical limiting have been in the scientific limelight in the few decades. Carbon nanotubes(CNTs) have attracted great interests owning to their unique structure, which exhibit superior electric and optical properties. It has been found that CNTs have excellent optical limiting properties owning to the wide limiting band, low optical limiting thresholds and so on. Recently, the optical limiting properties of all CNTs have been studied, including single-walled carbon nanotubes(SWCNTs), multi-walled carbon nanotubes(MWCNTs). As a wide band-gap semiconductor, titanium dioxide(Ti O2) has attracted great interests owning to its non-toxicity, low cost, chemical stability and higher photoactivity. In this paper, multi-wall CNTs(MWCNTs) coated with Ti O2 nanoparticles, which is named as MWCNTs/Ti O2, was prepared to improve the optical limiting properties of CNTs.In this paper, we mainly investigated the optical limiting properties of optical limiting properties through kinds of work as follows: the MWCNTs/Ti O2 nanocomposite was prepared through sol-gel method and dispersed by the rounded system; the MWCNTs/Ti O2 nanocomposite was characterized by UV-VIS Spectrophotometer, X-ray diffraction, transmission electron microscopy and scanning electron microscopy; Finally, the MWCNTs/Ti O2 nanocomposite was investigated with nanosecond pulses at 532 nm to study the nonlinear optical properties by using z-scan method.Chapter 1 described the fundamental state of the optical limiting, makes a summary on the development of CNTs and semiconductor materials. Chapter 2 introduced the z-scan method, and did the research on the theoretical mode of nonlinear optics. Chapter 3 analyzed the preparation of the MWCNTs/Ti O2 nanocomposite and characterization data. Chapter 4 discussed the result of z-scan measurement and made conclusions on the optical limiting mechanism of MWCNTs/Ti O2 nanocomposite. Chapter 5 presented several ways to fabricate the optical limiting devices of MWCNTs/Ti O2 nanocomposite and it provided the possibility to use this new material in practical applications.