Study On The Nonlinear Optical Properties Of A New Azobenzene Derivative

Nonlinear optical materials have a wide range of applications in optical switch, optical communication and optical limiting, and other fields. In recent years, the study on the property and the scientific mechanism of the new nonlinear optical materials is becoming more and more deeply. Nonlinear optical materials can be classified into an organic nonlinear optical material, an inorganic nonlinear optical materials and composite nonlinear optical material according to the chemical properties. The organic nonlinear optical materials have attracted widespread attention and becoming one of the researching hotspots with the advantages of fast nonlinear response, large nonlinear optical coefficient, low dielectric constant, high damage threshold and so on. The azobenzene compound is a traditional photonic material. Azobenzene and its compounds possess excellent optical response of photosensitivity, nonlinear optical properties and have a very promising future in the field of optical devices, optical information storage, and biomaterials,etc. Therefore, they have attracted widespread attention of researchers in recent years. Therefore, It has important scientific significance and strong application value to design and obtain new azobenzene derivatives with excellent nonlinear optical properties.This thesis mainly synthesized a novel azobenzene derivative containing oxazole group from the concept of molecular design and investigated its molecular structure and linear properties by employing absorption spectra and photoluminescence spectra. The optical nonlinearities of these two azobenzene derivatives and its gold nanopartical composite were measured by employing z-scan technology. The mechanism of the nonlinear optical characteristic was analyzed. By comparing the optical nonlinearities of azobenzene derivative and its gold nanopartical composite, the effect of the gold nanoparticals on nonlinear optical properties of the material was discussed. Some valuable references for deep studying these kinds of new materials of azobenzene compound can be provided.The main content of this paper is as follows:1. Two kinds of azobenzene derivatives were designed and synthesized, and their molecular structures were confirmed by employing nuclear magnetic resonance and elemental analysis.2. Z-scan technique was used to measure the third order nonlinear properties of these two kinds of azobenzene derivatives. The nonlinear absorption coefficient and nonlinear refractive index were calculated according to formulas. The results indicated that these two azobenzene derivatives showed higher nonlinear coefficients mainly due to the cooperation of the photo-alignment of azobenzene, large π-electron system and hydrogen bonds between solute and solvent. By comparison, the third-order nonlinear susceptibility of AOB- t8 is 2.11 times that of BN. It is mainly due to that AOB- t8 introduced oxadiazoles and benzene ring so that it is easier to flow for the electron clouds. Thus the third-order nonlinear susceptibility of AOB- t8 is higher.3. The composite was prepared by wrapping azobenzene derivatives around gold nanoparticals. The third order nonlinear properties of the composite were measured by z-scan technique. By comparison, the third-order nonlinear susceptibility of the composite is smaller, which was explained from the surface plasmon resonance and local field theory. The effect of the gold nanoparticals on nonlinear optical properties of the azobenzene derivative was discussed.