Negative Index Materials (NIMs), predicted by Veselago are perhaps the most exciting optical materials today. They are characterized by negative dielectric permittivity e and negative magnetic permeability µ. This leads to oppositely directed energy and momentum transport, negative refraction, and the amplification of evanescent waves. These in turn allow a wide variety of remarkably exciting applications, such as flat, apertureless lenses, ‘perfect’ lenses with sub-wavelength resolution, novel antennas, new beam steering devices, sensor protection strategies, novel band gap materials, high density optical storage, etc.
This MURI aims to realize NIMs where the negative index is the result of negative bulk permittivity and permeability in the VIS-IR range. The materials will consist of dispersions of metallic nanoparticles in a host matrix. The negative permittivity will be realized through the individual response, while the key negative permeability will be realized through the collective response of assembled nanoparticles. The nanoparticles will be orientationally ordered, forming a liquid crystal phase, and the host material itself may also be liquid crystalline. Materials will be created via self-assembly of nanoparticles with functionalized surfactants/tethers, and subsequently processed to form large area thick 3D films. Self assembly will result in µ‹0 on the nanoscale, it will also result in the formation 3D bulk NIMs; this is our key concept. Our strategy allows optimizing the materials response with respect to the competing factors of index magnitude, loss, dispersion and anisotropy. As a consequence of liquid crystallinity, these NIMs will be soft and responsive, allowing easy processing and switchability.