Research Fellows Directory
Dr Oleg Mitrofanov
University College London
My research is focused on application of Terahertz (THz) electro-magnetic waves for investigations of physical processes. Using THz waves, rather than the optical waves, to form images can provide useful information. THz waves offer a possibility to distinguish chemical compounds or cancerous tissues that appear visually indistinguishable. There are also scientific applications, such as investigations of the nature of electrical conductivity in new materials, in which
spectroscopy with THz waves can aid in better understanding of basic physical phenomena. Potential impact of THz imaging and spectroscopy goes beyond fundamental scientific studies. Development of devices operating at THz frequencies is instrumental for future communications and information processing.
The main limitation of THz imaging and spectroscopy is poor spatial resolution imposed by, what is known as, the diffraction limit. According to electromagnetic wave theory, the wave energy cannot be focused in a homogeneous medium to a volume with dimensions smaller than approximately one half of the wavelength. It implies that images of two point objects separated by less than one half of the wavelength of light merge and therefore can not be distinguished. It also implies that nano- and micro-scale objects, such as quantum dots, nanowires, or cells,
exhibit very weak interaction with THz radiation.
My research is focused on enabling applications of THz spectroscopy for analysis of sub-wavelength size objects through developing near-field microscopy methods for THz waves. This approach is based on local electro-magnetic interaction between the object and a special probe, rather than on wave propagation (used in conventional microscopy). This method is not limited by diffraction and can in principle provide spatial resolution of ~0.001 mm (better than 1/100th of the wavelength). Along with the development of THz near-field microscopy instrumentation, my research is focused on its applications.