The Structured Electromagnetic Materials group

				Metamaterial
						Metamaterial is an artificial composite material whose overall optical response is determined not only by its element materials, but also (sometimes more critically) by its geometrical composition. Metamaterials are argued to possess extraordinary optical properties not found in natural materials. Negative index is an example. Our activities on this subject involve transformation optics for designing novel photonic devices (e.g. cloaks), tunable metamaterial, as well as metamaterial for compact antenna design.
						While the concept of homogenization theory is easily being applied to the assymptotic long-wavelength limit, e.g. the microwave regime where true sub-wavelength structures may be fabricated with ease, the optical regime challenges the underlying hypothesis of a true subwavelength unit cell. This calls for a deeper understanding of possible ambiguities associated with the propagation of a multiple of branches of electromagnetic states, rather than just a single state as in the asymptotic limit.

 

				Plasmonics
						The strong enhancement and confinement of the optical field associated with surface plasmon excitation makes such structures important targets for research and advanced technological applications. Engineering, control, and manipulation of the surface plasmons with the aid of nanostructures could, for example, lead to miniaturized photonic circuits with significantly increased functionality and reduced cost. The present project seeks to further advance surface plasmon efforts by employing periodic metallic structures in surface enhanced techniques. Our aim is to explore new nanoplasmonic structures for use in optical techniques in bio-chemical sensing and analysis.
						Quantum mechanical effects in the metallic response are expected to become important when the mesoscopic unit-cell structures have features approaching the nano regime. The Friedel oscillations and edge-smearing have important consequences for the field enhancement occurring at otherwise geometrically sharp features such as the corners of   the triangle. In this project we consider quantum mechanical effects which are hardly addressed in the metamaterial community, where the optical properties are traditionally studied theoretically within the classical framework of Maxwells wave equations with the material response given by bulk properties, thus neglecting spatial dispersion of quantum mechanical origin.

 

 

The SEM group also involves the following research subjects:

• applications of metamaterical concepts for antenna design and wirelss-energy transfer
• fundamental limitations of slow-light propagation in photonic crystals
• light-matter interactions, quantum dots embedded in a strongly dispersive environment
• sensing of chiral molecules in strongly dispersive structured media
• quantum optics in disordered and strongly dispersive media
• structured low-dimensional electron systems

 

These research activities are financially supported through a number of national research grants including

• The Danish Council for Strategic Research through the
  Strategic Program for Young Researchers
  (DSF grant #2117-05-0037, PI=Mortensen)
• The Danish Research Council for Technology and Production Sciences
  (FTP grant #274-07-0080, PI=Mortensen, FTP grant #274-07-0379, PI=Xiao)

The group also participates in the following centres and projects

• NATEC
  Nanophotonics for Terabit Communications
  VKR Centre of Excellence
  www.natec.dtu.dk
• TOPANT

  Topology Optimization of Electromagnetic Metamaterials for Miniaturiztation of Wireless Communication Antennas
  www.topant.dtu.dk