Appl Phys B DOI 10.1007/s00340-010-3985-y FDTD modeling of realistic semicontinuous metal films U.K. Chettiar · P. Nyga · M.D. Thoreson · A.V. Kildishev · V.P. Drachev · V.M. Shalaev Received: 1 March 2010 © Springer-Verlag 2010 Abstract We have employed a parallelized 3D FDTD (finite-difference time-domain) solver to study the elec- tromagnetic properties of random, semicontinuous, metal films. The structural features of the simulated geometries are exact copies of the fabricated films and are obtained from SEM images of the films themselves. The simulation results show good agreement with the experimentally ob- served far-field spectra, allowing us to also study the non- U.K. Chettiar () · P. Nyga · M.D. Thoreson · A.V. Kildishev · V.P. Drachev · V.M. Shalaev Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA e-mail: chettiar@seas.upenn.edu P. Nyga e-mail: pnyga@purdue.edu M.D. Thoreson e-mail: mthoreso@purdue.edu A.V. Kildishev e-mail: kildishev@purdue.edu V.P. Drachev e-mail: vdrachev@purdue.edu V.M. Shalaev e-mail: shalaev@purdue.edu U.K. Chettiar Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, USA P. Nyga Institute of Optoelectronics, Military University of Technology, Warsaw, Poland M.D. Thoreson Graduate School for Advanced Optical Technologies (SAOT), Universität Erlangen-Nürnberg, Erlangen, Germany linear moments of the optical responses for these realistic nanostructures. These results help to further our understanding of the de- tails of the electromagnetic response of randomly structured metal films. Our results can also be applied in the optimiza- tion of random metal nanostructures and in the design of surface-enhanced spectroscopies and other plasmonic appli- cations. 1 Introduction Much of the recent work on simulating complex metal– dielectric structures has been focused in one of two cate- gories. Many metal–dielectric systems are periodic or ex- hibit a known geometry; these structures are studied numer- ically using finite-element methods, finite-difference meth- ods, or even analytical methods in some cases. The other cat- egory for numerical simulations of metal–dielectric compos- ites centers on modeling the system properties using macro- scopic parameters that are relatively easy to obtain, such as the use of volume filling fractions and constituent permit- tivities in Bruggeman’s effective medium theory (EMT) [1]. Unfortunately, neither of these categories of numerical sim- ulation approaches is directly applicable to random metal– dielectric structures with strongly interacting metallic ele- ments. This is due to the fact that simple models such as EMT do not take into account metal-particle interactions and therefore fail to properly predict important aspects of the film response, such as absorptance. While full-wave simula- tions such as FDTD would predict these responses properly, such numerical methods require a known geometry. Such exact geometries of random metal–dielectric films are essen- tially impossible to predict before fabrication. In this work,