Abstract

We show that the threshold for intrinsic optical bistability can be greatly reduced by using structured nanoparticles that consist of a nonlinear dielectric core with a metallic coating. Previous calculations based on metallic particles relied on the nonlinear response of the metal particles.¹ It has previously been shown that structured nanoparticles² can obtain a much larger nonlinearity and figure of merit than the metal alone. The calculations we present are based on the greater flexibility allowed by using structured nanoparticles to (i) obtain a local field enhancement in the dielectric core which can consist of a polymer or semiconductor material with a large non-linearity, (ii) obtain the surface plasmon resonance effect and local field enhancement effect by the metallic shell, and (iii) a reduction of the effective metallic loss contribution as the shell thickness is reduced. As in previous studies, ellipsoidal particle shapes can be used to further optimize the local field enhancement.¹ We report here results with a PDA polymer as a Kerr nonlinear medium in the core. The metallic shell consists of silver, gold, or aluminum, optimized for various frequency regions of interest. The switching threshold intensity can be reduced below 100 kW/cm².

© 1989 Optical Society of America