Interfacial layer effects on the enhancement factor and optical induced bistability in small spherical metal/dielectric composites

Abstract

In this thesis, we studied the enhancement factor of local field for pure spherical metal composite, small spherical metal/dielectric composite and optical induced bistability of metal/dielectric composites with interfacial layer in linear host matrices which has not been studded in the literature so far. For relatively small intensity of electromagnetic radiation the local field inside the small particles can be enhanced up to the inner atomic fields. This requires taking into account of the nonlinear part of the dielectric function, which in majority cases is proportional to the square amplitude of the incident electric field |E| 2 . For such cases the local field inside the particle is determined from the cubic equation with respect to |E| 2 . The single value of |Eh | 2 is able to activate three different values of the local field |E| 2 . Using the calculated enhancement factor of local field and the cubic equation of the optical induced bistability of the composite material, the parameters of the interfacial layer are calculated. We take positive, zero, and negative values which represents dielectric like, no interfacial, and metal like, respectively for the pure metal case. In the case of metal/dielectric for which we consider the interfacial layer particle the above mentioned properties are reversed so that it will be positive to realize the metal like properties of the interfacial layer. The analytical and numerical results show that the enhancement factor of local field is extremely enhanced and the optical induced bistability increased its domain.