Optical Bistable Properties In An Nondilute Suspension Of Coated Particles Witn Dielectric Anisotropy

This research investigated the effective nonlinear optical properties and optical bistability of composite of core-shell structured particles with dielectric anisotropy character under non-limit dilute condition. Based on our calculation, we showed that the system dielectric anisotropy can be enhanced by adjusting the strength of dielectric anisotropy and interfacial structure parameters. Our research supplied a theoretical reference for experimental obtaining granular composite materials with optimal third-order nonlinear susceptibility and optical bistability.In chapter I, we briefly introduced the on-going research status of optical bistability in granular composite system. Current research results indicated that the introduction of dielectric anisotropy and the application of core-shell structure are effective methods to enhance optical non-linear character. Thus, we decided to study the optical non-linear character of core-shell structured particles composite system with dielectric anisotropy.In chapter II, we carried out studies of effective nonlinear response of the dielectric anisotropy characterized core-shell structured granule composite system. Under Quasi-static approximation, based on the non-diluted condition, the analytical expression of the effective dielectric constant and third-order nonlinear susceptibility of granule composite system was obtained in our research. Our calculation result demonstrated that the maximum value of optical linear absorption peak and effective third-order nonlinear susceptibility of the system could be achieved simultaneously if appropriate interfacial structure parameters were chosen. Meanwhile, accompany with the increase of the strength of system dielectric anisotropy, the value of the appropriate parameter will decrease, however, the maximum value of Optical linear absorption peak and effective third-order nonlinear susceptibility will also decrease.In chapterⅢ, used spectral representation theory combining with self-consistent mean-field approximation, we studied the optical bistability phenomenon of dielectric anisotropy characterized core-shell structured granule composite system. Calculation results showed that both the strength of radial dielectric anisotropy and interfacial structure parameter strongly affected the optical bistability. When radial dielectric anisotropy is relative large, with the decrease of interfacial structure parameter, the granule composite system will consequently show bistability, double bistability, tristbility optical non-linear activity; when dielectric anisotropy decrease to certain degree, the threshold interfacial structure parameter of bistability will increase. Finally, we also discussed the effective non-linear optical character of the system, we found that if the strength of dielectric anisotropy is relatively large, the reflectivity of the granule composite system has one or several return wire accompany with the change of interfacial structure parameter.In chapter IV, we compared the optical bistability characters of three tri-component granule composite system. The comparison result showed that the dielectric anisotropy characterized core-shell structured granule composite system we have chosen can get more optimized non-linear optical character, which not just show optical bistability, also can bring double optical bistability and tristability.The main conclusion of our research has been given in chapter V.