What is it about?

Terahertz waves, which range from 0.1 to 3 THz, have significant potential for high-data-rate communications due to large untapped spectral bandwidth. Terahertz fibre communications employ a hollow dielectric fibre as a waveguide for terahertz waves, in order to facilitate the transmission of multi-GB/s data. Some attractive features of the fibre itself include flexibility, low attenuation, lightweight, high security, and so on. The key challenge facing this work is the design of interfaces that are at once physically feasible, and provide efficient, broadband matching. There are two such interfaces; one between the RTD and the photonic crystal waveguide, and the other at the point at which the waveguide interfaces with the terahertz fibre. In both cases, we favour tapered structures in order to transition incrementally between different wave impedances, and modal distributions. This takes the form of an exponentially-tapered co-planar strip line structure for the first interface, and a triangular-shaped silicon spike, which is inserted directly into the terahertz fibre in the latter case.

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Why is it important?

This work can open the door to new terahertz applications such as remote sensing, non-line-of-sight and secure communications. Ohmic loss in metals is a critical issue in the terahertz range, as both the output power of the transmitter and the sensitivity of the receiver are limited. Thus, the terahertz fibre can serve as a lightweight and efficient alternative to the more-conventional coaxial cable that is commonly used for the large electrical devices such as 8K displays, terahertz measuring equipment, and so on. In the future, lightweight, low-loss of photonic-crystal waveguides (~0.1 dB/cm) and terahertz fibres (<2 dB/m) may also find applications in server-to-server communications, automotive systems, and satellite internal communications.


Terahertz fibre communications is more compact, simple, and low power consumption in comparison to conventional fibre-optic communications systems. Flexible terahertz fibres can be used for non-line-of-sight communications at multi-Gb/s rates. Furthermore, the flexible terahertz fibres may also find uses in security and medical applications, in remote sensing, e.g. Key salient points in this work are the realization of a low-loss terahertz fibre, coupling between photonic-crystal waveguide and terahertz fibre, and integration of a resonant tunnelling diode with the photonic-crystal waveguide.

Xiongbin Yu
Osaka Daigaku

Read the Original

This page is a summary of: Terahertz fibre transmission link using resonant tunnelling diodes integrated with photonic-crystal waveguides, Electronics Letters, January 2019, the Institution of Engineering and Technology (the IET), DOI: 10.1049/el.2018.7686.
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