Terahertz fiber devices

The transmission line is one of the most fundamental components for the implementation of electromagnetic systems, such as electric cables and optical fibers for microwave and optic applications, respectively. The terahertz band, sandwiched between those two well-developed spectra, is not an exception. To meet such essential demand, low-loss, flexible, wideband terahertz fibers and corresponding functional devices have witnessed a blooming interest in the past two decades, being considered as a promising candidate for building compact, robust terahertz systems thus advancing the practicality and commercialization of terahertz science and technology. In this tutorial, we will provide a concise introduction to the fundamental characteristic parameters and prevalent hosting materials of terahertz fibers. Subsequently, we will look backward over the developments of terahertz hollow-core and solid-core fibers, as well as fiber-based terahertz functional devices for communication, sensing, spectroscopy, and imaging applications. Moreover, we will discuss several remaining challenges hampering the practical utilizations of terahertz fiber devices and propose some potential solutions to current major bottlenecks.