“Nanodevices for Terahertz Communication Systems”

When: April 25, 16:00

Where: Skoltech, E-B2-3006 (New Campus)

 CPQM seminar:

Nanodevices for Terahertz Communication Systems

 Dr. Shihab Al-Daffaie

Post Doc – Group Leader of Nanophotonics and Terahertz Technology (NTT)

Photonics and Optical Communications

Institute for Microwave Engineering and Photonics

Department of Electrical Engineering and Information Technology

Technische Universität Darmstadt


NEW device concepts and materials for the fabrication of compact terahertz (THz) nano-sources are of particular interest. THz waves at sufficient power from reliable sources are key requirements for many applications in medicine, chemistry, biology, physics, materials science, public safety, and information and communications technology. Such compact THz sources usually include optical laser mixing, Schottky diodes, varactor diodes for frequency multiplication, tunneling diodes, uni-traveling- carrier photodiodes or quantum cascade lasers. New types of continuous-wave (CW) THz photomixers were fabricated using 1-D and 2-D nanocontacts on low-temperature-grown (LTG) GaAs as well as nitrogen-ion-implanted GaAs. The 1-D and 2-D nanocontacts were formed by silver nanowires and graphene sheets, respectively. The 1-D photomixer of both configurations (lateral and vertical) produced a large reduction of the capacitance of around one order of magnitude as compared to conventional photomixers. The various hardware and software parameters of the wireless communication links therefore need to be optimized. Hence the development of compact, low-profile, inexpensive THz wireless communication system requires a careful and efficient design of high power sources, detectors and high gain antennas. The main objective of nanoelectronics engineering would therefore be to design miniaturized devices that are light, cheap and have low power consumption. Further the response time of the devices should be minimum in order to have fast processing and transmitting the information. Inability to implement nano-transreceivers at very high frequencies suggests the use of such nano-devices (Figure 1). Additionally, using Orbital Angular Momentum (OAM) multiplexing transmission technology in the millimeter-wave band has been attracting attention using high-frequency bands in the 2010s. The OAM is a physical quantity that expresses a property of electromagnetic waves in quantum mechanics. A key feature of electromagnetic waves differing in OAM is that they can be superposed and separated (principle of OAM multiplexing). One of the suggested THz systems has devised OAM-MIMO multiplexing transmission technology that combines OAM multiplexing transmission with widely used Multiple-Input Multiple-Output (MIMO) technology.


Dr. Shihab Al-Daffaie received the M.Sc. degree in satellite engineering from Al‐Nahrain University, Baghdad, Iraq, in 2008 and the Dr.‐Ing degree from the Institute of Microwave Engineering, Technische Universität Darmstadt, Darmstadt, Germany, in 2015. First, he worked on the field of ultrahigh‐frequency electronics, Terahertz, and nanotechnology within the framework of a doctoral scholarship funded by the German Academic Exchange Service (DAAD). Since October 2014, he has been working as a research associate at the field of THz and nanophotonics. He has employed his long experiences in the fields of conventional, embedded, and programmable electronics as well as microwave and optical communications. The team currently consists of himself and two PhD students including many Master students. He also leads a DFG as well as an EU project in the field of nanophotonics and terahertz technology.