Advanced Metamaterials

What is a “metamaterial”? Long before, people have dreamed of creating their own substances, which can be tuned at will instead of relying on what the Earth provides in raw form. With the advance of manufacturing technologies, the interest in fabricated structures and composite materials that either mimic known material responses or have new functions that do not occur or may not be readily available in nature has been revived. The peculiar properties of these metamaterials are generated by assembling microscopic and nanoscopic structures in unusual combinations. The underlying interest in the artificial materials is the potential ability to engineer the electromagnetic and optical properties of them for a variety of applications. The impact of them may be enormous: if one can tailor and manipulate the wave properties, many novel functions can be realized, from a perfect lens for making infinitesimal structures needed by the semiconductor industry, to a Harry Potter-style ‘invisibility cloak’, just to name a few.

The design flexibility associated with metamaterials provides a promising approach towards filling the “terahertz gap”. In our working group, the strong localization and enhancement of fields of metamaterial is utilized to detect minute changes of sample electromagnetic properties, enabling the detection of e.g. DNA, proteins or bacteria. Here, the structures are designed to have the desired response exactly at the spectral “sweet-spot” of the material of interest.

Our other focus is on reconfigurable metamaterials, or metadevices. The advancement of terahertz technology has long lagged behind because of the lack of available components for manipulating beams. Metamaterials provide many opportunities to actively tuning its interaction with radiation, by altering the shape of the individual metamolecule resonators, or by manipulating the near-field interactions between them. This enables a myriad of novel designs from microelectromechanical systems (MEMS) devices, utilizing electro-optical materials or liquid-crystals, to tuning semiconductors’ carrier densities. Our main concern here is on designing metamaterials that can be tiled as 1-D or 2-D array devices for imaging applications.

The working group emphasizes on the engineering aspect of metamaterial research: the whole chain of development, from concept, simulation and optimization, prototyping and testing, to manufacture and characterization of metamaterial based device is of our interest. Based on our knowledge on terahertz science and micro-fabrication techniques, our research is geared toward robust and mass-producible metadevices that meet the needs of real life application.