Abstract

Terahertz electromagnetic wave is one of the hottest research topics in nowadays scientific world thanks to its broad applications in material characterization, medical imaging, wireless communication, and security checking etc. Using free-electron beams to interact with periodic structures via the famous Smith-Purcell effect is an efficient way of generating high-power terahertz radiation. In this chapter, we introduce the basic theory and latest developments of the terahertz radiation schemes using a free-electron beam (including continuous electron beam, a single electron bunch, and a train of electron bunches, etc.) to interact with periodic electromagnetic structures, including grating, surface plasmonics, and subwavelength hole arrays, via a special Smith-Purcell effect or Cherenkov-like effect. A kind of free-electron lasers based on the special Smith-Purcell radiation in the terahertz region is proposed and investigated, which can be developed as high-power terahertz wave sources for practical applications.

Highlights

  • Terahertz electromagnetic wave is an attractive topic to researchers thanks to its broad application prospects in fields as diverse as biological imaging, materials science, and astrophysics [1]

  • The other one is the surface-current model based on the image-charge approximation [19, 20], according to which Smith– Purcell radiation (SPR) is generated from the surfacecurrent, induced by a moving electron beam, on the periodic metallic structure

  • We revealed a class of Special Smith-Purcell Radiation (S-SPR), which cannot be perfectly involved in the previous theoretical models mentioned above

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Summary

Introduction

Terahertz electromagnetic wave is an attractive topic to researchers thanks to its broad application prospects in fields as diverse as biological imaging, materials science, and astrophysics [1]. Compared with other kinds of terahertz sources, the free-electron driven sources, such as conventional vacuum electron devices (VEDs) [4] and free electron lasers (FELs) [5], can generate electromagnetic radiation with high power and desirable coherence. Developing new mechanisms or radiation schemes to improve the efficiency and power of SPR terahertz sources is the major goal of the present chapter, which is organized as follows. The other one is the surface-current model based on the image-charge approximation [19, 20], according to which SPR is generated from the surfacecurrent, induced by a moving electron beam, on the periodic metallic structure. Both models can deduce the SPR relation. A series of variants of S-SPR are proposed and investigated

S-SPR from one-dimensional gratings
S-SPR from two-dimensional sub-wavelength hole arrays
S-SPR from surface plasmonics
Terahertz free-electron sources based on S-SPR
Findings
Conclusions
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