Filling the THz gap—high power sources and applications

TLDR

Electromagnetic waves at 1 THz sit between photonics and electronics, are hard to generate and detect, yet match the energies of many key physical, chemical, and biological processes, driving major advances to fill this spectral gap. The review aims to describe the evolution of new generation THz sources that boost average power by over a million‑fold and to highlight the scientific opportunities now enabled. This power increase is achieved by combining relativistic electrons with super‑radiance. The resulting sources raise average THz power by more than a million‑fold, making the region routinely accessible for the first time.

Abstract

Electromagnetic waves centred at a frequency of 1 THz lie between photonics on the one hand and electronics on the other, and are very hard to generate and detect. However, since the THz part of the spectrum is energetically equivalent to many important physical, chemical and biological processes including superconducting gaps and protein dynamical processes, it is of great interest to facilitate experimental research in this region. This has stimulated major steps in the past decade for filling this gap in the usable spectrum. In this review paper we describe the evolution of a new generation of sources that boost the average power available in the THz region by more than a million-fold, making this region routinely accessible for the first time. This is achieved using two enhancement factors, namely relativistic electrons and super-radiance. We will also point to the scientific potential for discovery that is now enabled in this region.