# Key Roles of Plasmonics in Wireless THz Nanocommunications--A Survey
## 6 Summary and Conclusions
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Wireless THz Application** & **\begin{tabular}{} **\end{tabular}** & **Beyond \
\begin{tabular}{} **\end{tabular}** \\ \hline \multirow{4}{*}{NoCs} & PCB, 3D, FSO, IR & Graphene based WiNoCs \\ \cline{2-3}  & & Hybrid optical-wireless NoCs \\ \cline{2-3}  & Si photonic/nanophotonics & (plasmonic resonators with \\  & & dielectric waveguide) \\ \hline \multirow{4}{*}{WNNNs (wireless nanosensor networks)} & Graphene nanoribbon (GNR)/carbon nanotube (CNT) nanosensors, nanoprocessors, nanoantennas, nanotranseivers & Graphene (GFET) based THz antennas and transceiver parts \\ \cline{2-3}  & Nanoscale energy harvesting systems & \\ \cline{2-3}  & Au and Ag plasmon sensors & Nanomories \\ \hline \multirow{4}{*}{Beyond 5G communications} & Si photonics based uni-travelling photodiodes (UTC-PDs) and comb sources at mm waves &
\begin{tabular}{} \end{tabular} \\ \cline{2-3}  & & (IMWP) in THz, \\ \cline{1-1} \cline{2-3}  & & Plasmon or POH modulator (THz/O) \\ \cline{1-1} \cline{2-3}  & Graphene multiple-input-multiple-output (MIMO) antennas structures \\ \hline \hline \end{tabular}  
*SoA—state-of-the-art.  
\end{table} 
Table 1: SoA and beyond SoA technologies for wireless THz applications. well considered to be a promising THz transmitter approach. Moreover, plasmonic slot waveguides may be used as a perfect nanocoupler matching element with current state of the art on chip sources (nanoLEDs, nanolasers) (Table 2). Lastly, as far as concerns state of the art THz band receivers, waveguide integrated detectors using GaAs SBDs are considered as the most common implementation choice. However, they pose limitations on their size and available bandwidth, and behave poorly at room temperature. Si-CMOS technology with HEMTs has also been proposed for equipping detectors between 790 and 960 GHz, as they pose performance limitations above 1 THz. Hybrid plasmon structures, such as POH slot waveguide integrated with a bowtie antenna, or graphene slot photodetector on SOI, or GFET based structures such as plasmonic teraFET, are considered to be promising, beyond state of the art, THz wave detectors (Table 2). GFET based structures can be also used for equipping other THz transceiver parts, such as switches, LPFs, BPFs, phase shifters and modulators. Alternatively, PIPED structures, which are actually end to end, transmitter and receiver packages, monolithically integrated on a common silicon photonic chip platform, have been also proposed for THz wave signal generation and coherent detection, at frequencies of up to 1 THz (Table 2). Tables 1 and 2 include, in summary, all state of the art and beyond state of the art, plasmon based technology, exploited for the implementation of future THz band nanocommunication systems, as have been exhaustively presented in this work. Apparently it seems that, in order to fully equip future THz nanocommunication applications, miniature size transceiver components are required, with uncompromising features such as low propagation signal loss, impedance matching between link components, strong integration potentials and compatibility with ancestor technologies as CMOS, with high bandwidth availability and ultra-fast operating data rates and minimum latency.