Nanooptics with Plasmonic-Nanomaterials

Purdue University, West Lafayette IN

Investigators

Abstract

In this project, optical properties of nanomaterials with different structures will be theoretically studied. The fundamental problem to address is how the symmetry of a nanostructured material influences its optical properties and, related to this, what geometrical structure should be chosen for best performance of the material. We specifically focus on metal-dielectric crystals and composites that can support various plasmon modes, resulting in strongly enhanced optical responses. In our research we particularly consider local optical phenomena that occur in sub-wavelength, nanometer-sized areas of the material. We plan to study photonic crystals made of periodically structured metal, which we refer to as i) plasmonic crystals. The goal here is to develop robust band-gap materials, with large and scaleable gaps in the visible and near-infrared. Because of large and negative permittivity of metals, they are intrinsically gap materials and can dramatically improve performance of photonic band-gap crystals and ease their fabrication. By employing the skin effect that expels light from metal, losses can be dramatically decreased, which is a major foe for metals. By taking control of losses we hope to open new avenues for various applications of plasmonic crystals in photonics. By combining plasmonic crystals with submicron-sized resonators made of nearly percolating composites, we will develop ii) left-handed materials in the visible and near-IR, which have a negative refractive index in this spectral range. The plasmonic mesh-like crystals, in this case, can provide negative permittivity, whereas the composite resonators lead to negative permeability. Such material with simultaneously negative permittivity and permeability should have negative refraction. Another possibility for developing left-handed materials, which we also plan to explore, is based on periodical arrays of metal needles. The left-handed materials have unique optical properties and can find a number of novel applications, for example for developing super-lenses, which are capable of perfect image reconstruction. In these projects we also plan to study iii) light-managed extraordinary optical transmittance through an optically-thick metal film. This new idea stems from our recent theory that has successfully explained the earlier observed extraordinary transmittance through subwavelength hole arrays. Because of the optical Kerr nonlinearity of a film, the interfering light beams can result in a periodic modulation of the refractive index in the film. This modulation can act as a periodic "hole array," created by light itself, allowing the extraordinary light transmittance through the film. This idea, when developed into a theory, can open new avenues for manipulating light with light and for developing all-optical transistors, switchers, and modulators. %%% In this project, optical properties of nanomaterials with different structures will be theoretically studied. The fundamental problem to address is how the symmetry of a nanostructured material influences its optical properties and, related to this, what geometrical structure should be chosen for best performance of the material. We specifically focus on metal-dielectric crystals and composites that can support various plasmon modes, resulting in strongly enhanced optical responses. In our research we particularly consider local optical phenomena that occur in sub-wavelength, nanometer-sized areas of the material. ***