SHEWA GETACHEW2023-11-102023-11-102023-06-13In this work, we study the effect of tunable dielectric core of local field enhancement, inducedoptical bistability and it’s domain in small spherical metal-dielectric composite core. By ad justing the dielectric core and volume of the metal part of coated inclusions, the maximumvalue of the enhancement factor can be calculated. The host dielectric and the dielectric corare interfaced with the metal shell. The local field enhancement factor significantly rises atthese two resonant frequencies with increasing additional dielectric function on active dielec tric core. It is clear from the results, local field enhancement factor increases in as the additional dielectric function is added to dielectric core. The imaginary part of the dielectric core in active dielectric core has a negative sign because of that seems additional dielectric function is given to the dielectric core. By studying, the dielectric core has an effect that is enhanced by the presence of a local field in the surrounding region, resulting to an increased enhancement factor. The another fundamental point we study is optical bistabilityin which the intensity of output light can take two distinct stable values for a given input incident radiation, creating optical bistable for real states output and one absorbed for image binary part. We choose to provide a 2D and 3D graph in order to get a general understanding of the relationship between the applied field, local field, and dielectric core. By comparing three different values of local field to one value of applied field, it is possible to see that the instability region expands as the dielectric core increases. The typical dependencies of the induced optical stability domain on the active dielectric composite that are discovered by solving the cubic equation. The information from the curves enclosing the stability domain, namely the onset and offset stability fields at a specific frequency, is comparable to that from-type curves. The findings indicate that the induced optical stability domain expands asthe imaginary part of the dielectric function of the dielectric core ε00dincreased by applying additional dielectric function on it and the system enables to oscillate highly.enNonlinear Optics,Dielectric Core,Enhancement Factor,Optical Induced Bistability.Thesis