Nonlocality Ehanced Optical Bistability in Core-shell Structure

For decades, plasmonic metal have been used to support surface plasmons and to achieve nonlinear optical effects. This electronic dplasmonic metal have been used to support surface plasmons and to achieve nonlinear optical effects. With the development of nanotechnology, nano-sized metallic structure such as core-shell sphere or cylinder can be fabricated with very small size. For on-chip compact optical devices, however, in the extreme small regime, their optical responses will be affected by the nonlocal response of the metal, which in turns changes the nonlinear processes. Nonlocality and nonlinearity are expected in metallic /dielectric nanoparticle system, indicating deep significance in both fundamental research and design of new compact optical devices. These two freedoms will give the opportunity for us to seek for and manipulate more interesting physical phenomena in the microscopic world, hence contribute to the new thought of optical devices designing. In this article, we discuss dielectric/metal composite consisting of Kerr dielectric and nonlocal metal embedded in the host medium, and show the nonlocal effects of the inclusion can dramatically alter the near field configuration and far field scattering signals of core-shell structures. We demonstrate that nonlocality can significant reduce the switching threshold of the optical bistability and provide broader region in geometric parameter space for optical bistability, in both near field and far field. It suggests a nonlocality enhanced nonlinear optical devices