Abstract-Dispersion-limited versus power-limited terahertz communication links using solid core subwavelength dielectric fibers

                                                               

Kathirvel Nallappan, Yang Cao, Guofu Xu, Hichem Guerboukha, Chahé Nerguizian, and Maksim Skorobogatiy

Schematic of the THz wireless and fiber communication links for reliable and versatile intra-/inter-vehicle communication applications.

https://www.osapublishing.org/prj/fulltext.cfm?uri=prj-8-11-1757&id=441881

Terahertz (THz) band (0.1–10 THz) is the next frontier for ultra-high-speed communication systems. Currently, most of communications research in this spectral range is focused on wireless systems, while waveguide/fiber-based links have been less explored. Although free space communications have several advantages such as convenience in mobility for the end user, as well as easier multi-device interconnectivity in simple environments, fiber-based communications provide superior performance in certain short-range communication applications such as multi-device connectivity in complex geometrical environments (ex., intra-vehicle connectivity) and secure communications with low probability of eavesdropping, as well as secure signal delivery to hard-to-reach or highly protected environments. In this work, we present an in-depth experimental and numerical study of the short-range THz communications links that use subwavelength dielectric fibers for information transmission and define the main challenges and trade-offs in the link implementation. Particularly, we use air or foam-cladded polypropylene-core subwavelength dielectric THz fibers of various diameters (0.57–1.75 mm) to study link performance as a function of the link length of up to ∼10  m$\sim 10\mathrm{m}$, and data bit rates of up to 6 Gbps at the carrier frequency of 128 GHz (2.34 mm wavelength). We find that depending on the fiber diameter, the quality of the transmitted signal is mostly limited either by the modal propagation loss or by the fiber velocity dispersion (GVD). An error-free transmission over 10 m is achieved for the bit rate of 4 Gbps using the fiber of smaller 0.57 mm diameter. Furthermore, since the fields of subwavelength fibers are weakly confined and extend deep into the air cladding, we study the modal field extent outside of the fiber core, as well as fiber bending loss. Finally, the power budget of the rod-in-air subwavelength THz fiber-based links is compared to that of free space communication links, and we demonstrate that fiber links offer an excellent solution for various short-range applications.

© 2020 Chinese Laser Press

Abstract-Channel Multiplexing in Wireless Terahertz Communications Using Orbital Angular Momentum States

Kathirvel Nallappan, Hichem Guerboukha, Mohamed Seghilani, José Azana, Chahé Nerguizian, Maksim Skorobogatiy

(Submitted on 26 Aug 2017)

https://arxiv.org/abs/1708.08005

We present design and experimental validation of the system for the generation of the Orbital Angular Momentum (OAM) states using 3D-printed low-loss metamaterial phase plates for application in the terahertz (THz) wireless communications. By azimuthally varying the hole pattern density within the phase plate, the local effective refractive index is varied, thus also changing the local propagation constant in the azimuthal direction. The OAM of any topological charge can be created by simply varying the thickness of the phase plate. The phase plate with topological charge (m=1) is 3D printed and the amplitude and the phase of the terahertz signal after passing the plate is characterized using the THz-time domain imaging system. Finally, we present the experimental setup and theoretical simulation on the multiplexing and de-multiplexing of several different OAM states for applications in wireless terahertz communication.

Abstract-Transmission of Live Uncompressed 4K Video Using Terahertz Wireless Communication System

Kathirvel Nallappan, Hichem Guerboukha, Chahé Nerguizian, Maksim Skorobogatiy

https://arxiv.org/abs/1708.07721

(Submitted on 24 Aug 2017)https://arxiv.org/abs/1708.07721

We present the design and integration of Photonics based Terahertz wireless communication system using all commercially available system components. The performance of the developed system is then characterized by measuring the Bit error rate (BER) at the data rate of 5.5 Gbps as a function of communication link distance, angular rotation of the detector and bias voltage of the photomixer. With optimized threshold an error free transmission of 5.5 Gbps has been achieved over the link distance of 30 cm. Finally, the design for the integration of 4K camera with the THz communication system is discussed and the transmission of live uncompressed 4K video has been demonstrated successfully.