Dispersion Limited versus Power Limited Terahertz Transmission Links Using Solid Core Subwavelength Dielectric Fibers

TL;DR

This study investigates the performance of subwavelength dielectric fibers for short-range terahertz communication links, highlighting the impact of fiber diameter, dispersion, and bending loss on data transmission quality.

Contribution

It provides experimental and numerical analysis of THz fiber links, identifying key limitations and demonstrating error-free 10-meter transmission at 4 Gbps with small-diameter fibers.

Findings

Signal quality limited by modal loss or dispersion depending on fiber size

Error-free 10-meter transmission at 4 Gbps with 0.57 mm fiber

Fiber links outperform free space in power efficiency for short-range use

Abstract

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 main challenges and tradeoffs 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, and data bitrates 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 meters 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.