Study On Third-order Nonlinear Optical Properties Of Imidazolium Cation Ionic Liquids By Femtosecond Laser

Nowadays, more and more people are concerned for the study about the nonlinear optical properties of condensed matter. Seeking and finding new nonlinear optical materials has become the common needs of the scientific research and industry.Ionic liquids, as a new type of "soft" functional materials, has attracted an increasingly widespread attention for its good nature, and played an increasingly important role in many fields. However, studies and reports on ionic liquids are widely concentrated in the chemical catalysis, synthesis and separation, and electrochemical properties. Research on nonlinear optical properties is rarely reported. In recent years, ultra-short and high-intense pulse laser, especially the rapid development of femtosecond pulse laser has provided a powerful research tool for the study of the interaction between light and matter, and the study of ultra-fast nonlinear optical phenomenon. And this has become the key to explore and discover mysteries about the process of instantaneous changes of matter.In order to explore and verify third-order nonlinear optical properties of the ionic liquids, and based on the theory of nonlinear optics and the Z-scan experimental method, we independently designed the Z-scan experimental program using femtosecond pulse laser with the wavelength of810run, and completed a facility for the femtosecond laser Z-scan experiment in this thesis. Through the open aperture (OA) Z-scan experiment, we have researched the nonlinear optical properties of four typical ionic liquids and got curves of the open aperture (OA) Z-scan experiment. The results show that the nonlinear optical absorption properties of1-butyl-3-methylimidazolium nitrate ([BM Im]NO3) are more obvious and prominent than the other three types of imidazolium cation ionic liquids. Under the action of810nm femtosecond pulse laser, the laser filamentation phenomenon of imidazolium cation ionic liquids was firstly observed by us. At the same time combined the experimental device, we used the theory on matrix optics, ABCD Law and Collins formula of laser optics to do a theoretical analysis about the entire optical experimental system. And the results are almost the same as the experimental results. By using femtosecond lasers, we also measured optical absorption properties about the liquid core of the four types of imidazolium ionic liquids. This has provided an experimental basis for the further application in the field of Information Photonics.