Investigation On Controling The Characteristic Of Sbs

As the development of nonlinear phase conjugate technology, stimulated Brillouin scattering (SBS) has been receiving more and more attentions and applied to extensive fields. Compared with other nonlinear phase conjugation, SBS phase conjugation technology plays a more important role in obtaining optical phase conjugation with the characteristics of small frequency shift, simple structure, high fidelity and high reflectivity. In addition, the reflective light of SBS can realize pulse compression while the transmitted light can achieve optical limiting; therefore the research of the characteristics of has become very significant in the field of nonlinear optical phase conjugation.In this thesis, two methods of controling the characteristic of SBS are proposed. The two methods are based on changing media temperature and mixing media respectively. Numerous studies show that the properties of the medium have a great influence on SBS. Excellent performance of SBS medium can greatly improve the characteristics of SBS, so the research of SBS medium is a wonderful approach to further improve and control the SBS characteristics. Currently, the study of SBS medium mainly focused on discovering new media, however the new medium finding needs not only a long period of time to research and experiment, but also relatively high cost. Therefore, by optimizing the performance of existing medium to control the characteristics of SBS is a simple and effective method.In the research, the medium parameters affecting the characteristics of SBS have been investigated firstly. The results show that kinematic viscosity is a very important parameter since gain coefficient, phonon lifetime and further the SBS characteristics are greatly influenced as kinematic viscosity changing.Secondly, a series of perfluoropolyether (PFPE) liquids with excellent performance have been introduced. The PFPE, with all the H atoms linking the C atoms replaced by F atoms, exhibits low absorption coefficient and high power-load ability. In the experiment, the SBS characteristic of new media such as HT-230, DET and HS-260 are measured.In addition, control characteristics of SBS based on medium temperature changing is investigated.The correlation between temperature and SBS is established by the viscosity-temperature characteristics of medium. The variations of absorption coefficient and energy reflectivity with temperature changing are investigated in experiments. Moreover, the variation laws of the SBS with temperature are also analyzed. In the final part, control characteristics of SBS based on mixed medium is investigated. As the parameters of mixed mixture change with the mixing-ratio, the mixed medium not only can optimize the media, but also can control the characteristics of SBS within a certain range. The dependence of parameters on mixing-ratio are simulated by the Matlab sotfware, and validated in the experiment.