Nonlinear Terahertz Generation: Chiral and Achiral Meta-Atom Coupling

摘要

Generation and manipulation of terahertz (THz) waves are of vital importancefor advancing THz technology. Nonlinear metasurfaces allow effectiveintegration of both processes into a single compact device. However, suchexisting THz devices commonly rely on utilizing a single meta-atom, whichhas fixed THz generation properties and thus limits the range of achievablefunctionalities. Here, it is demonstrate how coupling between different metaatomswithin the unit-cell can be used as a degree of freedom for controllingnonlinear THz generation, where achiral coupling provides full control overthe amplitude of the generated THz field, while chiral coupling makes theTHz generation sensitive to the handedness of the pump polarization. Inparticular, chiral coupling allows the realization of multiplexed pump-handedness-selective nonlinear metasurfaces, which is illustrated experimentally byselectively generating THz beams with different orbital angular momentumwith a single nonlinear metasurface. This approach provides opportunities fordeveloping various integrated nonlinear THz devices.