The terahertz and mid-infrared spectral region is most suited for the study of novel optical materials and phenomena. We study, for example, THz polaritonics with metamaterials and quantized transitions in semiconductors, light-matter interaction of optical nano-antennas and semiconductor quantum dots and novel two-dimensional materials like graphene or MoS2. 

 

Our group investigates graphene and related materials, such as atomically thin transition metal dichalcogenides, for applications in electronics and optoelectronics. The aim of our work is to advance state-of-the-art of nanodevice technology and provide physical insights in carrier dynamics, energy level schemes, optical response, and many body effects in these materials. 
(Nanoscale Electronics and Optoelectronics Group homepage)

 

Typical RF antennas are used to impedance-match a sub-wavelength oscillator, such as an RF circuit, to free space. In much the same way we aim to improve the light-matter interaction of our sub-wavelength devices, InAs quantum dots, by attaching them them to nano-antennas. By tuning the nano-antennas' resonance frequency to the optical frequency of the quantum dot we aim to increase the interband and intersubband optical relaxation rates.
(G. Lilley, M. Messner)

Metamaterials (MMs) are artificial optical materials that consist of regular arrays of subwavelength sized metallic resonators. They constitute an exciting possibility for the efficient coupling of free-space radiation to a wide variety of quantum systems. The combination of such metasurfaces with quantized transitions in semiconductors leads to a whole new range of applications. Examples include large-area surface-emitting quantum-cascade lasers and photodetectors, coherent terahertz amplifiers, and active THz modulators.  See our CLEO 2015 Poster
(C. Derntl, M. Wenclawiak, J. Darmo)