Nonlinear Terahertz Generation: Chiral and Achiral Meta‐Atom Coupling

Abstract

Generation and manipulation of terahertz (THz) waves are of vital importance for advancing THz technology. Nonlinear metasurfaces allow effective integration of both processes into a single compact device. However, such existing THz devices commonly rely on utilizing a single meta‐atom, which has fixed THz generation properties and thus limits the range of achievable functionalities. Here, it is demonstrate how coupling between different meta‐atoms within the unit‐cell can be used as a degree of freedom for controlling nonlinear THz generation, where achiral coupling provides full control over the amplitude of the generated THz field, while chiral coupling makes the THz generation sensitive to the handedness of the pump polarization. In particular, chiral coupling allows the realization of multiplexed pump‐handedness‐selective nonlinear metasurfaces, which is illustrated experimentally by selectively generating THz beams with different orbital angular momentum with a single nonlinear metasurface. This approach provides opportunities for developing various integrated nonlinear THz devices.

Real-Time Terahertz Modulation Using Gold-MoS2 Metasurface With Electromagnetically Induced Transparency-Like Resonance

“…The development of metamaterials has emerged as a breakthrough approach with unique electromagnetic properties, including negative refractive index [2], [3] and perfect lensing [4] capabilities, which are unattainable with conventional materials. This study targets metasurface devices with narrowband resonances for advanced THz modulation [5], [6], [7], stressing the significance of achieving electromagnetically induced transparency-like (EIT-like) resonances [8], [9] with higher quality (Q) factors.…”

Generation of a Focused THz Vortex Beam from a Spintronic THz Emitter with a Helical Fresnel Zone Plate

“…TVBs have potential applications in high-speed THz communication, THz imaging, and atom trapping [ 6 , 7 , 8 , 9 , 10 ], and the generation of a TVB has been an important topic in the past few years [ 11 ]. Recently, by introducing electromagnetically induced transparency coupling to control nonlinear THz generation, a TVB with a different OAM was achieved [ 12 ]. Lu et al reported that a hybrid nonlinear plasmonic metasurface incorporating indium tin oxide can be used to generate a TVB [ 13 ].…”