Recent advances in generation of terahertz vortex beams and their applications*

Abstract

Last decade has witnessed a rapid development of the generation of terahertz (THz) vortex beams as well as their wide applications, mainly due to their unique combination characteristics of regular THz radiation and orbital angular momentum (OAM). Here we have reviewed the ways to generate THz vortex beams by two representative scenarios, i.e., THz wavefront modulation via specific devices, and direct excitation of the helicity of THz vortex beams. The former is similar to those wavefront engineering devices in the optical and infrared (IR) domain, but just with suitable THz materials, while the latter is newly-developed in THz regime and some of the physical mechanisms still have not been explained explicitly enough though, which would provide both challenges and opportunities for THz vortex beam generation. As for their applications, thanks to the recent development of THz optics and singular optics, THz vortex beams have potentials to open doors towards a myriad of practice applications in many fields. Besides, some representative potential applications are evaluated such as THz wireless communication, THz super-resolution imaging, manipulating chiral matters, accelerating electron bunches, and detecting astrophysical sources.

Spin-orbit coupling induced by ascorbic acid crystals

“…It would be interesting to explore the STOC phenomena in other kinds of spherulites, which may have advantages over ascorbic acid. In particular, recently the controlled generation of quartz spherulites [32] may offer an interesting way for creating vortex beams in the Tera Hertz frequency domain [33] (qplates for this regime have been recently realized using either 3D printing techniques [34] or quartz segmented waveplates [35]) It would also shed light on the role of different crystal structures and symmetries in the shaping of light.…”

Forty-five terawatt vortex ultrashort laser pulses from a chirped-pulse amplification system

“…As a consequence, some new theoretical concepts are proposed, e.g. vortex particle beam accelerations [14], strong magnetic field generation [15], intense terahertz vortex [16], vortex high-order harmonic generation [17], and so on. However, the corresponding experimental verification is devoid due to the lack of a high-quality terawatt/petawatt (TW/PW) vortex laser.…”

THz Multi-Mode Q-Plate with a Fixed Rate of Change of the Optical Axis Using Form Birefringence

“…Even if today the available structures in the THz regime are still limited, due to the constraint of the present techniques of light manipulation, THz beams carrying optical angular momentum have been proposed in many applications, ranging from THz communications to super-resolution imaging and the investigation of nonlinearities in advanced materials and systems [ 2 , 3 , 4 ], and even to accelerate and manipulate electron bunches [ 5 ]. For instance, coherent high-field THz radiation from ultrashort relativistic electron bunches is generated by accelerator-based sources, where the super-radiant and the high field emission require density modulation at THz frequencies [ 6 ].…”