ECE PhD Proposal Review: Arjun Singh

PhD Proposal Review: Design, Modeling and Operation of Plasmonic Devices for Smart Communication Systems in the Terahertz Band

Arjun Singh

Location: Teams Link

Abstract: The terahertz (THz) band is an attractive spectral resource for future communication systems, for supporting very high-speed data rates and increasingly dense networks. However, the lack of a well-developed technology that operates at these frequencies has remained a challenge for the scientific community. The very high propagation losses at THz frequencies and the decimating impact of everyday objects on THz wave propagation necessitate an up-haul of the conventional communication link, with smart control over the radiation, propagation, and detection of THz signals. To overcome these obstacles, novel plasmonic devices that exploit the attractive properties of graphene have been proposed. However, there are several challenges, such as low output power and high reflection losses, that are not yet addressed. The objective of the proposed research herein is to facilitate an end-to-end communication link with graphene plasmonics as the cornerstone of the fundamental device physics. The devices designed can be utilized at both the communication endpoints, as well as across the channel, to effectively overcome the limited communication distance – The grand challenge of the THz band.
To this end, a graphene-based plasmonic array architecture is first proposed, explained, and modeled. The fundamental radiating element of the array architecture, called the plasmonic front-end, consists of a self-sufficient plasmonic source, a plasmonic modulator that acts as a phase controller, and a plasmonic nano-antenna. The array designed through an integration of these front-ends is compact and provides complete beamsteering support, with a new tailored algorithm developed for beamforming weight selection. Numerical evaluations and full-wave finite difference frequency domain (FDFD) simulations with COMSOL Multi-physics are utilized to verify array operation. The array is also demonstrated to provide a strong effective isotropic radiated power (EIRP), that increases exponentially with array size. To mitigate the negative effects of the channel environment, such as unwanted blockages and high path losses for simpler devices, a hybrid reflectarray is presented. The fundamental element is modeled as a jointly designed and integrated metal-graphene patch. Numerical and simulation results are utilized to demonstrate the attractive properties of the proposed reflectarray as compared to other proposed counterparts, including independence from the incoming angle of the impinging wave, dynamic phase control capability, and a strong reflection efficiency. The unique design properties of the plasmonic array, as well as the hybrid reflectarray, open the option of incorporating techniques such as multi-beam beamforming design and interleaved, independent arrays, to boost the channel capacity.
As a part of the proposed work, the impact of the design properties of these devices on the communications link will be investigated by developing the fundamental problem and considering all trade-offs. The undertaking will be significantly more robust and conclusive than those that have been performed previously, both due to the consideration of a complete end to end link, as well as the incorporation of the characteristics of the device design model. Finally, preliminary fabrication results in the realization of these devices are presented, and the roadmap ahead is outlined.