A Plasmonic View on THz Emission from fs Laser induced Microplasmas
Résumé
Terahertz (THz) sources are indispensable for various applications such as THz time-domain spectroscopy. Often broadband THz emission spectra are highly demanded, but inaccessible by conventional sources as photoconductive switches, quantum cascade lasers or nonlinear crystals. In the last decade, laser-induced-gas-plasma-based sources turned out to emit sometimes ultra-broadband THz emission. When trying to explain this broadband THz emission, the current literature overlooks the analogy between laser-induced gas plasmas and plasmonic structures: In both, plasmon-polariton-like resonances can play a significant role. We show by extensive 3D Maxwell-consistent numerical simulations and simplified modeling that plasmon-polariton-like resonances can broaden the THz emission spectra.