Numerical investigations of metal-dielectric structures

Contacts:

Andrei Lavrinenko, DTU Fotonik 4525-6392 (alav@fotonik.dtu.dk)

Alexandra Boltasseva, DTU Fotonik, 4525-6368 (albo@fotonik.dtu.dk)

Dielectrics are known to have very low losses, but as a result they have very moderate influence on the photon fluxes. In contrary, metals affect light propagation a lot, however, by price of intensive attenuation of any optical waves happened to impinge on their surface. The modern trend in nanophotonics is to combine metals and dielectrics together to get advantages by using unique properties of such composites.

By incorporating specially designed nanoscale metallic clusters in dielectric so called metamaterials are produced. Some extravagant properties like negative refraction can be obtained, that can lead, e.g. in really fantastic world of “invisible cloak” [1].  Another way of making metal-dielectric combinations is to deposit thin metallic layers on top of dielectric substrates, then plasmonics waves can be excited (see the sketch). In both cases it is possible to enhance control the flow of light together with reduced losses.

We aim to investigate properties of metamaterials and/or plasmonic waves by use of numerical methods. One of the most universal is the finite-difference time-domain method which directly solves the Maxwell equations in two-three space dimensions. Typically it is used to simulate properties of light in dielectrics. To adjust it to problems of light propagation in metal-dielectric composites frequency response of metals has to be taken into account. Implementing such models in the finite difference scheme will allow simulating either metamaterials properties or plasmonic waves propagation for broad range of nanoscale designs. Another option is to utilize the software packages available for intensive computations at DTU Fotonik.

[1] D. Schurig, J.J. Mock, B.J. Justice, S.A. Cummer, J.B. Pendry, A.F. Starr, D.R. Smith, Metamaterial Electromagnetic Cloak at Microwave Frequencies, Science, vol. 314, pp. 977 – 980, 2006.